Mrs. Gentrie seemed somewhat overawed by the importance of her visitor. Aunt Rebecca and Delman Steele, sitting together at the dining-room table working a crossword puzzle, looked up as Mason introduced himself to Mrs. Gentrie. They stood up as Mrs. Gentrie escorted Mason toward them.

Mrs. Gentrie performed the introductions. “Mr. Mason, the lawyer you’ve read about,” she announced. “This is my husband’s sister, Miss Gentrie.” It was always necessary to emphasize the “Miss” in introducing Aunt Rebecca. So many people were inclined to call her Mrs. if they hadn’t been paying attention when the introduction was performed, and that led to a correction later which, somehow, always seemed like an embarrassing explanation. “And Mr. Steele, a roomer, who is also a crossword addict,” Mrs. Gentrie added.

Aunt Rebecca was by no means overawed. She looked Mason over critically, said, “Humph! You don’t look so formidable. Reading about you, I’d always imagined you bristled with hostility like a battleship.”

Mason laughed, sized up Delman Steele, a young man in the twenties, who met his eye steadily enough, yet who seemed, somehow, on the defensive. He was good looking, and there was plenty of character in his face, but something about the tight line of his lips indicated that he might, perhaps, have something to conceal.

Mrs. Gentrie said, “Mr. Steele is usually at his work by this time, but after what happened next door, the police insisted on holding everyone here — except they did let the two younger children go to school. Junior, that’s the oldest, is around somewhere. Here he is coming up from the basement now. Junior, come and meet Mr. Mason, the lawyer. He’s here because he — well, what are you doing here, Mr. Mason?” she asked as Junior shook hands with the lawyer.

“Just investigating the case,” Mason said.

“You have a client who’s interested in it?”

“Well, only indirectly. Not the person who’s charged with murder.”

“Have they charged anyone yet?”

“No,” Mason said and laughed. “That’s why I can speak with assurance when I say I’m not representing the person who’s charged with the murder.”

He turned to study Junior, a lad of about nineteen, who had a high, sensitive forehead which seemed at odd variance with the thickness of his lips. However, his nose was straight and well proportioned, and Mason realized that while the young man would never be considered as a matinee idol, he was, nevertheless, sufficiently good looking to get by nicely with the opposite sex.

Junior looked at the dictionary on the table in front of Aunt Rebecca. “No wonder that’s never in my room,” he said. “Every time I have to use it, I put in half an hour looking for it.”

Aunt Rebecca rattled into quick reproach. “Now, Junior, don’t be selfish with your things. After all, it doesn’t wear your dictionary out to look up a word once in a while. You should learn...”

“And my flashlight,” Junior interrupted. “Somebody’s always taking that and running the batteries down.”

“Why, Junior,” Mrs. Gentrie said, “I don’t know what you’re talking about. I only borrowed it for a few minutes yesterday when I was looking at the preserves on the shelf in the cellar. I didn’t have it on for as much as a minute or a minute and a half altogether.”

“Well, somebody must have left the switch on for a while,” Junior said. “The batteries were all run down this morning.”

“Perhaps you used it last night.”

He said, “That’s the point. I couldn’t find it last night.”

“Why, I put it back in your room. I...” Her voice suddenly lost its assurance, and Junior, wise in the ways of family life, said, “You mean you intended to put it back in my room, but I suppose you left it hanging around some place.”

“I... well, perhaps I did leave it down here. I had that basket of mending, and I put it... Where did you find it, Junior?”

“In my bedroom this morning.”

“Wasn’t it there last night?”

He shook his head.

Mrs. Gentrie laughed and said, “Well, Mr. Mason isn’t interested in all of our domestic troubles. That’s the way it is with a large family, Mr. Mason. Someone’s always feeling that his rights are being infringed upon.”

Aunt Rebecca said, “Well, I suppose Mr. Mason wants to ask us a lot of questions, but before he does, I’m certainly going to take advantage of his being here to find out about that thing that was bothering us in the crossword puzzle.”

Mrs. Gentrie said, “Oh, Rebecca, don’t intrude your silly...”

“If I can help, I’ll be only too glad to,” Mason said. “Fire away.”

“It’s a five-letter word, and the second two letters are u-a. It’s a legal term, meaning — what is it, Delman? How did they express it?”

Steele ran his finger down a list of numbers and then said, reading, “A legal term meaning ‘as if; as though; as it were.’ ”

“Five letters?” Mason asked.

“That’s right.”

The lawyer frowned a moment, then said, “Why not try quasi?”

Rebecca grabbed up the pencil, lettered in the word, moved her head back, and perked it on one side as though she had been a bird critically examining a dubious bug. “Yes,” she said abruptly, “that’s right! That’s absolutely right! That’s exactly what it is. Quasi. I never heard of it before.”

“It’s a term used extensively by lawyers,” Mason said.

“Well,” Rebecca announced, “that is going to get us over the hump, Delman. I suppose Mr. Mason wants to know everything — just as the police did...”

“Please be seated, Mr. Mason,” Mrs. Gentrie invited.

As Mason sat down, Rebecca said, “I certainly hope you don’t start asking a lot of questions, Mr. Mason. I’m all on edge. I started this crossword puzzle to try and quiet my nerves. Mr. Steele’s been kind enough to help me on quite a few of them. Do you do crossword puzzles, Mr. Mason?”

“I’m afraid I don’t have much time for them.”

“Well, perhaps I should be doing something else — and yet I don’t know what else to do. I think it’s a lot better to do crossword puzzles than just fritter away your time. After all, Mr. Mason, it does do wonders for your vocabulary.”

“I assume it does,” Mason said.

Mrs. Gentrie said, “Come, Rebecca. Mr. Mason’s time is valuable. He didn’t come here just to talk about crossword puzzles.”

“Well, I don’t want to start talking about that murder again. It all happened yesterday when you upset me with that story about the empty can. I haven’t been able to concentrate since.”

“Empty can?” Mason asked.

Mrs. Gentrie said indulgently, “That’s just a household mystery. You mustn’t mind Rebecca. She’s always digging up little household mysteries.”

“ I’m interested in mysteries,” Mason said, his eyes twinkling. “I collect mysteries the way your sister-in-law collects crossword puzzles.”

“Well,” Rebecca said, “I wish you’d solve this one, Mr. Mason. I just can’t get it off my mind.”

“Rebecca!” Mrs. Gentrie rebuked.

“No, go ahead. I’d like to hear it,” Mason said. “I really would.”

Mrs. Gentrie, evidently quite embarrassed, said, “It was nothing, Mr. Mason. I went down in the cellar yesterday to check over the tins and jars of preserved fruit, I found an empty tin on the shelf.”

“Just an empty tin?” Mason asked.

“Yes.”

“No. That isn’t all of it,” Rebecca interpolated. “It was an absolutely brand new tin, Mr. Mason. It had been put up on that shelf with the preserves. There wasn’t any label on that tin, and it had been sealed up — you know, crimped over, the way you seal preserves in a can.”

“You have one of those sealing machines here?” Mason asked.

“Yes. We put up a good deal of fruit and vegetables. Some we put up in jars, and some we put up in tins. We have a sealing machine which crimps the top on.”

“And this can was empty?”

“Just exactly as it came from the store,” Mrs. Gentrie said.

Rebecca said, “It wasn’t any such thing, Florence. The more I think of it, the more I realize there was something strange about that can. A can isn’t hermetically sealed when it comes from a store.”

“What did you do with the tin?” Mason asked.

“Tossed it in the box of old tins,” Mrs. Gentrie said, laughing.

“You didn’t open it to look inside?”

“Gracious, no. It was too light to have had anything in it. It was just an empty can.”

“But you didn’t look inside to make certain it was empty?”

Rebecca said, “Arthur did that. That’s Florence’s husband, Mr. Gentrie, you know.”

“Was he here when you found it?”

“No. He was looking around for a tin to mix some paint in last night. He found this tin down in the box.”

“It was empty?” Mason asked.

“That’s what he said.”

Delman Steele said, “I saw the can, Mr. Mason. I went down in the basement last night to ask Mr. Gentrie a question. He was painting around the woodwork of the windows, and the door which leads to the garage. I asked him if he’d seen the tin...”

Rebecca interrupted, “ I’m the one that asked Mr. Steele to go down and dig that tin up. I just couldn’t get it off my mind.”

Steele laughed and said, “And thereby almost got me in bad with this lieutenant who’s investigating the shooting next door.”

“How did that happen?” Mason inquired.

“He was checking up on all of the persons who had been down in the basement last night,” Steele said. “I sometimes go down to chat with Arthur Gentrie or look in on Miss Gentrie when she’s in her darkroom. But I don’t think I’d have gone down last night if it hadn’t been for Miss Gentrie asking me about the can.”

“What’s being in the basement got to do with the murder?” Mason asked.

Steele said, “It’s beyond me. Tragg was down there prowling here and there, then came back and asked a lot of questions.”

Rebecca said, “I’m going to put a lock on my darkroom door. They pulled the door open and flung the dark curtain to one side, let daylight stream in, and fogged half a dozen films for me. Personally, I think the police should be more considerate.”

Mason said, “I find myself getting interested in that can. You say that Mr. Gentrie had used it to mix paint in, Mr. Steele?”

“That’s right. I guess it’s still down there.”

“How did he open it?”

“Oh, there’s a can-opening machine down there in the cellar.”

Rebecca said, “I’m certain you’ll agree with me, Mr. Mason, that it’s something that should be looked into. That tin didn’t grow on the shelf. It was a brand new tin. It hadn’t been there long — and why should anyone hermetically seal up an empty can?”

“I’m certain I don’t know,” Mason said.

“Well, neither do I, but someone did.”

“You mentioned a garage door,” Mason said to Steele. “That’s a door which communicates with the garage where Mr. Hocksley keeps his car?”

“That’s right,” Mrs. Gentrie said. “There’s a double garage with one door leading to the cellar. You see, the house is built on a sloping lot, and the ground is so steep they made the cellar in two levels. I presume the house was built before the days of automobiles — or at least before people appreciated the importance of having a garage in connection with the house. Then, later on, someone remodeled that end of the basement so as to include a two-car garage. We keep our machine in one of them, so we have the other one for rent. The side that has the door to the cellar is a little the more desirable, so we rent that, and, of course, use that door to the cellar to come in and out of our house, particularly when it’s rainy.”

Mason said, “If you don’t mind, I’d like to take a look at the garage.”

“You can come right down the cellar stairs, Mr. Mason, and open the door — or you can walk around the sidewalk and come in through the garage door.”

“I think I’d prefer to go in through the cellar.”

Mrs. Gentrie said, “If you’ll just come this way, Mr. Mason.”

Rebecca firmly pushed the dictionary and the crossword puzzle to one side, got to her feet, and smoothed down her skirts. “If you think you’re going down in that cellar with Mr. Mason and talk about that empty can, and have me sitting up here where I can’t hear what you’re saying, Florence Gentrie, you’re very much mistaken. The more I think of it, the more I think that empty tin may just as well as not be a clue to what happened.”

“How could it be a clue?” Mrs. Gentrie asked, her eyes twinkling.

“I don’t know,” Rebecca said firmly, “but it might just as well be. Don’t you think so, Delman?”

Steele’s laugh was magnetic. “Don’t involve me in a family argument,” he said. “I just room here. They take me in as one of the family — but I’m not a charter member. I am not entitled to take part in the discussions.”

Mrs. Gentrie laughed. “I’ve never drawn the line there, Delman. When you rented that room and asked if you could move in as one of the family, I told you there was only one thing that was absolutely forbidden — and that was the privilege of the telephone.”

She turned to Mr. Mason, smiling, and said, “We should have three lines in here. What with three children all making dates and scrambling for the phone every time it rings, I sometimes think I’ll smash it — and I can never get to it in the morning or evening to place my orders at the grocer’s or call up my own friends.”

Rebecca said, “We were talking about the tin, Florence.”

Junior said, “Your clutch is slipping, Aunt Rebecca. How the heck could an empty tin have anything to do...”

“Junior!” Mrs. Gentrie broke in. “No one asked you for your opinion. Come on, Mr. Mason, down this way.”

They all trooped after the lawyer down to the cellar. Mason looked the place over. Mrs. Gentrie pointed out where she had found the tin. Junior showed him the door leading to the garage. Mason tested the paint with his finger. “This what Mr. Gentrie painted last night?” he asked.

“A quick-drying enamel of some sort,” Steele said by way of explanation. “Mr. Gentrie runs a hardware store, you know. This was a sample of a new brand of paint one of the salesmen for a paint company had given him. He wanted him to try it out. He was telling me about it last night.”

“It’s necessary to mix it?”

“Half and half with some thinner,” Steele explained. “Gentrie seemed to think it was a distinct improvement over any other of the brands he’d been handling. It comes in two cans. One of them has the color; and the other is some sort of a quick-drying thinner. You mix the two together, half and half, and apply. It’s supposed to dry within six hours.”

Mason indicated a spot near the garage door. “Someone evidently didn’t know it had been freshly painted. It looks very much as if someone, groping for the doorknob in the dark, got his hands on the paint.”

“It does for a fact,” Steele said.

“Let me see,” Junior insisted, pushing forward with an eager curiosity.

Steele said, “That’s odd. I hadn’t noticed that before. I was down here with the police, too. It’s just a little smear.”

Mason said, “The paint’s dry now. You say it dries in six hours?”

“Yes, four to six hours. That’s what Mr. Gentrie told me. Of course, that’s the only way I have of knowing.”

“Let’s look for that tin,” Rebecca said, moving along the workbench, sniffing and peering at the assortment of tools. “Here’s a can with paint brushes in it. Could this be it, Delman?”

“That’s it,” Delman said. “You can always tell the way Mr. Gentrie opens a can. He never runs the opener all the way around. He stops just before he cuts the lid entirely free. He always leaves a strip of tin of about a sixteenth of an inch, then twists the lid off.”

“That’s right,” Mrs. Gentrie confirmed. “He says that if you go farther than that, the top of the can falls down on the inside. I always hold up the lid and then finish cutting. Arthur twists. You can see where the top of this can was twisted off.”

Mason thoughtfully regarded the tin. “Let’s take a look at the top of the can just to make our investigation complete,” he said.

“At the top of the can!” Mrs. Gentrie asked.

Mason nodded.

“Well, probably we can find it if we look through this box of scraps, but, for the life of me, I can’t see what...”

Steele said, “I noticed it lying here on the bench last night. There it is, over there near the corner. He used it to set a paint can on.”

Mason picked up the circular tin top and examined the distinctive place where it had been twisted off.

“This the one?” he asked.

“That’s it,” Steele said. “I remember that little distinctive twist on the tin. You can see where it was turned...”

Mason’s eyes showed keen interest. “Wait a minute,” he said. “This isn’t right.”

“What’s wrong with it?”

Mason said, “The lid that was on the tin was twisted off to the left. This one is twisted off to the right.”

Steele bent forward and regarded the circular piece of tin, then went over to look at the can. “Well, I’ll be darned,” he said. “I saw that piece of tin lying here on the counter last night and naturally supposed it had come off this can. Why in the world would Mr. Gentrie have opened the can, thrown the top away, then taken the top from another tin out of that box of scraps? But Gentrie is left-handed. You’re right about that top — but, why...?”

“I don’t know why,” Mason said, “but that’s very evidently what he did. Let’s take a look over here in this box of scraps.”

Rebecca said tartly to Mrs. Gentrie, “I told you it had something to do with what happened over there. You can see what happens when a trained mind starts working on the problem.”

Mrs. Gentrie sighed. “I’m afraid I’d make a poor detective,” she said. “It certainly seemed trivial enough.”

Mason smiled. “I’m afraid I’m like your sister-in-law Mrs. Gentrie. Whenever there’s anything the least bit out of the ordinary, I start making a mystery out of it. After all, you know, it is rather a peculiar place for an empty tin, and I can’t imagine why anyone would seal up an entirely empty tin. There must have been something in it.”

“Well, I shook it and didn’t hear anything. And goodness knows the can was light enough to be empty. It couldn’t have had anything in it. Of course, now that I see everyone making so much of a point of it, it...”

“And unless I’m mistaken,” Mason, who had been leaning over the scrap box, interposed, “this is the top which came off the can.” He reached down into the tangled mass of tin.

“Watch out you don’t cut your hand in there,” Mrs. Gentrie warned sharply.

Junior laughed and said, “Mr. Mason doesn’t need to be a detective to tell you’re the mother of three children, Ma. ‘Don’t do this, and don’t do that.’ ”

Mason straightened up with a piece of tin in his hand, walked over to the can in which the paint brushes were deposited, and held the circular piece of tin over the top so that the little twisted nipple of tin which had been left on the can was placed against the corresponding point on the circular piece.

“That’s it all right,” Steele said.

Junior reached out eagerly. “Gee, Mr. Mason, let me take a...”

“Junior,” Mrs. Gentrie rebuked, “don’t interfere with what Mr. Mason is doing.”

Mason said, “The underside seems to be all scratched up. It feels rough to the touch. Let’s just examine those scratches. We’ll tilt it over here near the window so that the light comes across it from the side, and...”

“It’s a code,” Rebecca shrilled excitedly. “Something written on there... scratched on the tin! I knew it! I just knew it! I told you so, Florence. You wouldn’t listen to me, but...”

Mason whipped a pencil from his pocket and tore a sheet of paper from his notebook. “Will someone write these letters as I read them off?” he asked.

Rebecca said eagerly, “I will.”

Mason handed her the paper and pencil, tilting the lid, so that he could get a side lighting on the letters as he read.

“CKDACK CJIAJ DLACC HEDBCE CEIADD GIKADC CLDGBD KFBCH CLGGBJ.”

Mason took the piece of paper from Rebecca and carefully checked the letters she had written with the original.

“I don’t see how this could have had anything to do with what happened across the street,” Mrs. Gentrie said, frankly puzzled.

Mason slipped the sharp-edged circle of tin into the side pocket of his coat. “It may be just a coincidence,” he agreed. “Rather peculiar, that’s all. How many of you heard the shot?”

“I did,” Mrs. Gentrie said.

Steele said, “I was sleeping soundly, and was wakened by the noise. I suppose it was all over when I woke up, but I tried to reconstruct what had wakened me, and somehow had the impression there were two shots.”

“Did you mention that to Lieutenant Tragg — the head of the Homicide Squad?” Mason asked.

“I don’t think I did,” Steele said. “He seemed quite positive there was only one shot, and I didn’t contradict him. Of course, my impressions were very vague, just trying to recall a noise which has wakened you from a sound sleep. It’s just a vague feeling, anyhow — an echo in the back of the consciousness, if you know what I mean.”

Mason said, “I know exactly what you mean, and you express it very well indeed. It might be a good plan for you to get in touch with Lieutenant Tragg and tell him that, after thinking it over, you believe it’s very possible there were two shots.”

“There weren’t,” Rebecca said positively. “Only one. I was wide awake at the time. I thought it might have been a backfire from an automobile or truck. I know there was only one shot.”

Mason turned to Junior, raised his eyebrows.

Junior shook his head. “I can’t help you at all. I slept right through the whole commotion. I couldn’t have been in bed very long when it happened either, probably not more than fifteen or twenty minutes.”

“What time was the shot?”

“Around twelve-thirty, I believe.”

“What time did you get to bed?”

“Ten or fifteen minutes after midnight. I just shed my clothes all over the room and dove into bed. I’d been out with a young lady, and had taken her home. I thought I was going to have to work today, and — well, I just can’t seem to get enough sleep.”

Mrs. Gentrie said solicitously, “Junior, don’t you think you should tell Mr. Mason with whom you spent the evening?”

Junior colored. “No,” he said shortly.

“I noticed that you avoided mentioning her name to that Lieutenant— What’s his name?”

“Tragg,” Mason prompted.

“No need of dragging a woman into this,” Junior said hotly.

“Junior, was it...” Mrs. Gentrie started to ask.

“Don’t you mention any names,” he interrupted with intense feeling. “I don’t want you snooping around in my affairs. It’s bad enough to have Rebecca always camping on my trail. My gosh, I’m grown up and big enough to take care of myself. I don’t go around snooping into your...”

“Junior!”

“All right, I’m sorry, but don’t you mention any names. I mean that. This is stuff that gets in the papers, and I don’t see that it makes a particle of difference who I was with.”

Rebecca said, “Well, what are we going to do about that code message on the can? Here we are, standing talking and letting the murderer slip through the fingers of the police.”

Mason said, “Let’s be certain about that can before we do anything. You feel quite positive you didn’t put it up on that shelf with the preserves, Mrs. Gentrie?”

“I know I didn’t, and I don’t think Hester did either. She’s stupid at times, but certainly not that stupid. Furthermore, I don’t think that can had been there for more than a day or two at the most. I don’t see how it could have... well...”

Mason said, “Well, let’s notify Lieutenant Tragg of exactly what happened, and he can draw his own conclusions. After all, that’s his business.”