She regarded him with that whimsical expression which a woman reserves for a man of whom she is very fond and who has been rather clumsy in seeking to outwit her.

  “Something wrong with that?” Mason asked.

  “Dr. Sawdey is a doctor. If he leaves, it will be on a call.”

  Mason nodded.

  “And it would be on an urgent call. Therefore, he’ll leave in an automobile. I suppose you’re going to run after him on foot?”

  Mason said, “No. I just want to know if he goes, not where he goes.”

  Della Street placed a hand on his arm. “Now, Perry, my lad, listen to me. You’ve got something up your sleeve. If there’s going to be any housebreaking, I’m going to be just as deep in the mud as you are in the mire.”

  “What makes you think I’m going housebreaking?”

  “Don’t be silly!”

  Mason said, “It’s a felony. It’s dangerous. In case we get caught, we can’t very well make explanations.”

  “All the more reason, then, why you should have an accomplice.”

  “No. It’s too dangerous. You go to the restaurant, and . . .”

  “Bosh! I’m going to stay with you. Do we take the cab or . . .”

  Mason said, “We get rid of the cab right here.” He walked over to the driver, handed him a bill, and said, “The change is yours, buddy. We’re supposed to be back in ten minutes. The doc’s going to have a prescription ready by that time. So we’ll just walk around.”

  “I could wait,” the cabby said, “if it’s only going to be ten minutes, and . . .”

  “No, thanks. We’re visiting friends in the neighborhood after that, so it won’t pay to wait.”

  The cabby touched his hat and drove off.

  Della Street said, “Here we go! Embarking on a career of crime! If I’m going to be an accomplice, I may as well learn crook jargon and talk out of one side of my mouth. What am I, a steerer?”

  Mason said, “No. You’re a moll. You’re going to case the lay.”

  She walked with an exaggerated swing to her hips, said out of one side of her mouth, “Cripes, Chief, I’m the moll who can give you de office in case a harness bull tries to queer de act. I’ll stroll on past an’ give him de eye, an’ . . .”

  “And get yourself arrested for soliciting a self-respecting police officer on the street,” Mason interposed.

  “Well, what of it? Ain’t you de mouthpiece that can spring me? Why should I take a rap when I got de swellest mouthpiece of ’em all on my string? Maybe you could slip the beak a grand an’ square the pinch. But right now we got a crib to crack. We can’t waste time. . . .”

  She stopped as she heard a distinctly startled gasp behind her. Looking up, she saw Mason grinning broadly, saw an elderly gentleman who had noiselessly approached from behind on rubber-soled shoes, regarding her with shocked consternation. Then, with a muttered, “Pardon me,” he had pushed on past, walking so rapidly that his feet seemed to be hardly touching the sidewalk.

  Della Street muttered under her breath, “Good heavens, did he get an earful!”

  “Did he get an earful!” Mason chuckled. “He acted as though he had two ears full.”

  “Where did he come from?”

  “I don’t know. I just happened to turn my head and caught a glimpse of him pussyfooting along behind. His face looked as though he’d suddenly received the bill for his new income tax.”

  “You don’t think he could have been following us?”

  Mason shook his head. “Not that chap. He’s some mousy retired bird who lives somewhere in the neighborhood. You certainly gave him something to think about. The way he whisked himself around that corner, you’d have thought he was a puppet someone was jerking on a string.”

  Della Street said, “I thought I was putting on a swell act. My walk alone must have been enough to startle him. I felt like Fatima, the sideshow Turkish dancing girl.”

  “Well,” Mason said, “he’s got something to tell his friends now. He’s really seen a moll in action. What’s the number of this house where Luceman lived?”

  “Thirteen-o-nine Delington.”

  “That’s in the next block. Now listen, when I go in, you stand out by the curb. The minute you see anyone coming along the sidewalk, no matter who it is, walk up to the front door and ring the bell once. Don’t seem to hurry. Don’t act self-conscious, and, above all, don’t look back over your shoulder. Simply walk up and ring the bell, making your action look as natural as possible.”

  “Ring it once?” she asked.

  “That’s right. Now, if that person should turn toward the house, ring the bell three times, three short, sharp rings. When you have done that, turn to walk back toward the street, and then apparently see this person for the first time. You can smile and say, ‘There doesn’t seem to be anyone home.’ Then go to the next house and ring the bell. When someone comes to the door, ask them if they’re taking the Chronicle. Tell them you’re representing the newspaper and would like very much to take their subscription on a special introductory offer. Talk loudly enough so you can be heard across to the next house.”

  “Suppose he doesn’t wait that long but goes right on in?”

  “It’s all right,” Mason said, “just so you give me those three short, sharp rings on the doorbell the minute you see he’s heading toward the house. That’ll give me time to get out.”

  “Not much time,” she said, “particularly if you’re on the second floor.”

  “It’s all right,” he told her. “It’ll take a man a little while to get in, and it doesn’t make any difference if I don’t get out of the back door until he unlatches the front door—just so I get out. After all, there’s not very much chance it will happen. We’re just playing safe. That’s all. Be absolutely certain the minute anyone shows up anywhere on the street, to give me a signal on the bell. I’ll probably have to use the flashlight, and a person who happens to see the beam of light reflected against the window glass might call the police.”

  “And that’s all I have to do?” she asked.

  “That’s enough.”

  “You’re not trying to make things easy for me just to keep me out of it?”

  “No.”

  “You take care of yourself?”

  “I’ll try to.”

  “How are you going to get in?”

  “I’ll try the back door and actually cut through the screen just to make Luceman’s burglar come to life.”

  She placed her hand on his arm. “Take care of yourself, Chief,” she said in a low voice.

  “I intend to.”

  “There’s no good telling you not to take any risks,” she said, “because you aren’t built that way. You could no more sit in your office, wait for business to come in, and handle it in an orthodox manner than a trout could live in stagnant water. But do keep an eye open.”

  “Okay, I will, and if you have to start back to town, meet me at. . .”

  “Locarno’s Grill,” she interrupted. “Over the biggest, thickest filet mignon in the place.”

  Mason looked rapidly up and down the sidewalk, surveyed the dark outlines of the two-storied frame house, said, “Okay, Della, here we go. Keep your eyes open, and remember the signals.”

  He started as though headed for the front steps, then suddenly detoured to pass around between the houses. A small flashlight hardly larger than a fountain pen gave him suffioient illumination to show the cement walk which led around to the back of the house.

  An inspection of the back door showed Mason that entering the place was not going to be as easy as he had anticipated. The screen door was unhooked, but behind it was a wooden door equipped with a formidable lock, a lock which had cost much more than the average backdoor lock. A casual inspection of the windows showed that they were locked tightly, and there was something in the unshaking rigidity of the window frames which indicated the locks were more efficient than those a nocturnal prowler would ordinarily expect to find.

  Puzzled, as well as interested, Mason returned to the back door. His small flashlight once more explored the lock. He turned the knob and tentatively pushed against the door. It was anchored as firmly as though it had been embedded in concrete.

  Mason raised the flashlight to inspect the small square glass panels in the upper part of the door, and then suddenly realized that someone had been there ahead of him.

  The putty which held one of the panes of thick glass in place had been neatly cut away, so that a pane some eleven by fifteen inches was now held in place only by four small brads which had been driven into the wood at the corners of the panel.

  It took Mason but a few moments to get these brads removed. Then with the blade of his penknife, he was able to pull the glass toward him, so that it dropped gently into his extended palm. Thereafter, it was a simple matter to reach through the opening, find the knurled brass knob on the inside of the spring lock, turn it, and open the door.

  When Mason had the door opened, he took the precaution of putting the square of glass back into place and inserting the small brads so that it was once more held in position. In doing this, the realization that someone had anticipated him in his entire procedure was a disquieting thought.

  This person, Mason realized, had gone about his work with the cunning skill of a good technician. The putty had been carefully removed with a knife. The dried particles had been gathered up so that there would be no telltale clue left on the threshold or on the wooden floor of the back porch. Replacing the pane of glass with the four brads so neatly and precisely driven into the corners of the supports had made the door seem quite all right to a casual observer.

  Mason was just closing the door when he heard the sharp sound of a buzzer cutting through the fog-swept silence of the night.

  So explosive was the sound, and so engrossed had he been in the problem which confronted him, that Mason gave a convulsive start as the warning signal sounded. Then, tense with the effort to listen for every sound, Mason stood waiting. When nothing happened, he turned the knurled knob of the lock, and threw the catch which left the bolt held back. He slipped out to the porch, gently closing the door behind him. He could hear no steps, but as he neared the front of the house, he saw a dark form drifting past on the sidewalk, walking so rapidly that it seemed he must almost be running. Mason realized that it was the man who had passed them a few minutes earlier. Probably some neighboring householder, he reassured himself, who had gone down to mail a letter at the mailbox, or to a corner drugstore to replenish some toilet articles.

  Moving silently, Mason walked around the house to reassure Della. He gave a low whistle as he saw her standing on the front porch in the position of one ringing the bell.

  She came over to the railing at the edge of the porch, and said in a hoarse whisper, “My same little man. He came around the corner as though he’d been shot out of a gun.”

  Mason said, “He probably lives here in the neighborhood. I’ve got the back door open, Della. I’m going in.”

  “Don’t you think we’d better call it off, Chief?”

  “No. I only want to give the place a quick once-over. That old man has probably forgotten all about you by this time.”

  She said in a whisper, “I don’t forget that easily.”

  “Okay. Sit tight. You hadn’t better go back to the curb. Your friend might have another errand to run. If he saw you crossing from the curb to the door for the second time, he’d get suspicious. Just stand here in the shadows of the porch. If anyone comes along, be ringing the bell. Remember the signals. I want to know when anyone comes along the street. Don’t get rattled. I may even have to turn on the lights.”

  “Just what are you looking for?” she asked.

  Mason dismissed the question with a wave of his hand, and once more retraced his steps to the rear of the house. Back inside the kitchen, he debated whether to leave the back door unlocked, but finally decided to release the catch and let the spring lock remain in position.

  His flashlight showed him a conventional kitchen. Stale smells of ancient cooking clung to the woodwork. The linoleum was worn almost through in front of the kitchen sink and in front of the stove, the places which would naturally receive the most wear.

  The icebox was electric, and the modern freshness of its white enamel stood out against the darker finishings of the kitchen. It gave the impression of having been recently installed.

  Mindful of the story of the nocturnal cat, Mason opened the icebox door. As he did so, an electric light flashed on, illuminating the immaculate white of the interior.

  Here was food such as a lone bachelor might cook for a quick repast, a saucer containing what evidently represented the half of a can of beans which had not been eaten. There was a full quart of milk, and a bottle which was half emptied. A dish contained a quarter-pound square of butter, still in its original tissue wrapping, and a smaller piece of irregular shape. There was a small bottle of whipping cream, a jar of mustard, some sliced boiled ham which had evidently been picked up at a delicatessen store, and a small pasteboard container holding macaroni salad of the type featured by virtually every delicatessen counter.

  There were other odds and ends in the icebox, but Mason didn’t stop to explore them. The quick inventory which he took told all he needed to know. He noticed that the milk and cream were still sweet. The temperature regulator on the icebox was set at a point which would hold the contents at a low temperature. The food smelled sweet and clean, but with an ice box of this efficiency, that meant absolutely nothing. The food might have been left there yesterday or last week.

  Mason closed the door of the icebox, let his small flashlight cover the kitchen in a quick survey. Then he moved on into the dining room.

  His flashlight gave him a general idea of the furniture, an old-fashioned assortment which had evidently been purchased years before. The dining-room rug was new and cheap. The surface of the table had been refinished. The chairs had evidently been gone over with furniture polish, but the incongruity of the new dining-room rug simply made it all the more apparent that someone, after having lived in the house for years, had decided to rent it furnished, and had made an attempt to replace only the things which had been the most worn.

  Mason moved on through the dining room and into the living room.

  Here were bookcases built in on each side of a fireplace, wide windows fronting on the porch. The drapes on these windows seemed relatively new, and Mason realized with some apprehension that while these drapes had been pulled so that they entirely covered the front windows, the material was not heavy enough to shut out all light. The beam of Mason’s flashlight would quite probably show through from the street, and the small rectangular windows placed high in the wall above the bookcases on each side of the fireplace were not curtained at all. Della Street could warn him of any approaching pedestrian, but persons in the adjoining houses would be apt to notice the traveling beam of the flashlight as it moved around the walls.

  Mason’s problem was not that of an ordinary prowler. He needed his flashlight for more than mere illumination to enable him to avoid furniture. He wanted to make a detailed study of the things in that room, to seggregate those things which had been furnished with the house, so that he could more fully appreciate the significance of those things which had been brought in by the tenant.

  Mason hesitated only a moment. Then he walked across toward the front door and pressed the light switch.

  Instantly the room was flooded with brilliance. Mason found several floor lamps, turned these on. He opened a book, placed it face down on the table. In case some curious neighbor might be peering in through those uncurtained windows above the fireplace, he removed his hat and slowed down his motions so that they would seem to be the casual moves of a legitimate tenant, rather than the hasty motions of a prowler.

  An automobile driven at high speed slewed around the corner. Tires shrilled in protest as the car slid to an abrupt stop. The doorbell rang—once. Mason paused, motionless.

  He heard the businesslike slam of a car door. The doorbell rang three short, sharp rings. Mason heard running steps as someone dashed past the living room, running along the cement walk toward the back of the house. Once more there were three rings, then the sound of heavy steps on the porch.

  Mason, conscious of Della Street trapped on the front porch, reached an instant decision. He turned the brass knob which released the bolt on the front door, opened the door, said, “Good evening,” to his white-faced secretary who was standing on the threshold. “Was there something I could do for you?” he asked, and then, apparently for the first time, became conscious of the police car at the curb and the broad-shouldered plainclothes officer who was standing just behind Della Street.

  “Good evening,” Mason said cheerfully. “Are you together?”

  Della Street said quickly, “No. I am soliciting subscriptions for the Chronicle. We have a very attractive—”

  “Just a minute, sister. Jus-s-s-s-t a minute!” growled the officer.

  Della Street turned to survey him with hostile eyes. “Thank you,” she said acidly. “I’m trying to make a living at this, and I don’t want to see any etchings. Just because I’m unescorted doesn’t mean a thing—to you.”

  Mason said, “Won’t you come in?” and to the officer, “And what can I do for you?”

  The officer came pushing in on Della Street’s heels.

  “Really,” Mason said with the polite indignation of an outraged householder, “My invitation was to . . .”

  The officer threw back his coat, disclosing a badge. “What’s going on here?” he asked.

  Mason let his face show startled surprise. “Why! . . . That’s what I’d like to know.”

  The officer said, “We’re in a radio car. A man who lives a block down the street telephoned that he heard a couple of crooks planning on cracking a joint.”