The brothers led him to a table in the center of the office. On it there was a flat cabinet, with a lid of ordinary thin glass framed by a narrow rectangle of wood. Under the glass reposed a number of mounted stamps, lying nakedly on a field of black satin. In the center of the satin lay a leather case, open; its white lining had been denuded of its stamp. Where the lid of the cabinet had been wrenched open there were the unmistakable marks of a “jimmy,” four in number. The catch was snapped and broken.

  “Amatchoor,” said Sergeant Velie with a snort. “You could damn near force that locked lid up with your fingers.”

  Ellery’s sharp eyes were absorbed in what lay before him. “Mr. Ulm,” he said, turning to the wounded dealer, “the stamp you call ‘the one-penny black’ was in this open leather box?”

  “Yes, Mr. Queen. But the leather box was closed when the thief forced open the cabinet.”

  “Then how did he know so unerringly what to steal?” Friederich Ulm touched his cheek tenderly. “The stamps in this cabinet were not for sale; they’re the cream of our collection; every stamp in this case is worth hundreds. But when the three men were here we naturally talked about the rarer items, and I opened this cabinet to show them our very valuable stamps. So the thief saw the one-penny black. He was a collector, Mr. Queen, or he wouldn’t have chosen that particular stamp to steal. It has a funny history.”

  “Heavens!” said Ellery. “Do these things have histories?”

  Heffley, the man from the insurance company, laughed. “And how! Mr. Friederich and Mr. Albert Ulm are well known to the trade for owning two of the most unique stamps ever issued, both identical. The one-penny black, as it is called by collectors, is a British stamp first issued in 1840; there are lots of them around, and even an uncanceled one is worth only seventeen and a half dollars in American money. But the two in the possession of these gentlemen are worth thirty thousand dollars a piece, Mr. Queen—that’s what makes the theft so dog-gone serious. In fact, my company is heavily involved, since the stamps are both insured for their full value.”

  “Thirty thousand dollars!” groaned Ellery. “That’s a lot of money for a little piece of dirty paper. Why are they so valuable?”

  Albert Ulm nervously pulled his green shade lower over his eyes. “Because both of ours were actually initialed by Queen Victoria, that’s why. Sir Rowland Hill, the man who created and founded the standard penny-postage system in England in 1839, was responsible for the issue of the one-penny black. Her Majesty was so delighted—England, like other countries, had had a great deal of trouble working out a successful postage system—that she autographed the first two stamps off the press and gave them to the designer—I don’t recall his name. Her autograph made them immensely valuable. My brother and I were lucky to get our hands on the only two in existence.”

  “Where’s the twin? I’d like to take a peep at a stamp worth a queen’s ransom.”

  The brothers bustled to a large safe looming in a corner of the office. They came back, Albert carrying a leather case as if it were a consignment of golden bullion, and Friederich anxiously holding his elbow, as if he were a squad of armed guards detailed to protect the consignment. Ellery turned the thing over in his fingers; it felt thick and stiff. It was an average-sized stamp rectangle, imperforate, bordered with a black design, and containing an engraving in profile view of Queen Victoria’s head—all done in tones of black. On the lighter portion of the face appeared two tiny initials in faded black ink—V. R.

  “They’re both exactly alike,” said Friederich Ulm. “Even to the initials.”

  “Very interesting,” said Ellery, returning the case. The brothers scurried back, placed the stamp in a drawer of the safe, and locked the safe with painful care. “You closed the cabinet, of course, after your three visitors looked over the stamps inside?”

  “Oh, yes,” said Friederich Ulm. “I closed the case of the one-penny black itself, and then I locked the cabinet.”

  “And did you send the three invitations yourself? I noticed you have no typewriter here.”

  “We use a public stenographer in Room 1102 for all our correspondence, Mr. Queen.”

  Ellery thanked the dealers gravely, waved to the insurance man, nudged Sergeant Velie’s meaty ribs, and the two men left the office. In Room 1102 they found a sharp featured young woman. Sergeant Velie flashed his badge, and Ellery was soon reading carbon copies of the three Ulm invitations. He took note of the names and addresses, and the two men left.

  They visited the collector named John Hinchman first. Hinchman was a thick-set old man with white hair and gimlet eyes; He was brusque and uncommunicative. Yes, he had been present in the Ulms’ office two mornings-before. Yes, he knew Peters. No, he’d never met Beninson before. The one-penny black? Of course. Every collector, knew of the valuable twin stamps-owned by the Ulm brothers; those little scraps-of paper bearing the initials of a queen were famous in stampdom. The theft? Bosh! He, Hinchman, knew nothing of Beninson, or whoever it was that impersonated Beninson. He, Hinchman, had left before the thief. He, Hinchman; furthermore didn’t care two raps in Hades who stole the stamp; all he wanted was to be let strictly alone.

  Sergeant Velie exhibited certain animal signs of hostility; but Ellery grinned, sank his strong fingers into the muscle of the Sergeant’s arm, and herded him out of Hinchman’s house. They took the subway uptown.

  J. S. Peters, they found, was a middle-aged man, tall and thin and yellow as Chinese sealing-wax. He seemed anxious to be of assistance. Yes, he and Hinchman had left the Ulms’ office together, before the third man. He had never seen the third man before, although he had heard of Beninson from other collectors. Yes, he knew all about the one-penny blacks, had even tried to buy one of them from Friederich Ulm two years before; but the Ulms had refused to sell.

  “Philately,” said Ellery outside to Sergeant Velie, whose honest face looked pained at the word, “is a curious hobby. It seems to afflict its victims with a species of mania. I don’t doubt these stamp-collecting fellows would murder each other for one of the things.”

  The Sergeant was wrinkling his nose. “How’s she look now?” he asked rather anxiously.

  “Velie,” replied Ellery, “she looks swell—and different.”

  They found Avery Beninson in an old brownstone house near the River; he was a mild-mannered and courteous host.

  “No, I never did see that invitation,” Beninson said. “You see, I hired this man who called himself William Planck, and he took care of my collection and the bulky mail all serious collectors have. The man knew stamps, all right. For two weeks he was invaluable to me. He must have intercepted the Ulms’ invitation. He saw his chance to get into their office, went there, said he was Avery Beninson…” The collector shrugged. “It was quite simple, I suppose, for an unscrupulous man.”

  “Of course, you haven’t had word from him since the morning of the theft?”

  “Naturally not. He made his haul and lit out.”

  “Just what did he do for you, Mr. Beninson?”

  “The ordinary routine of the philatelic assistant—assorting, cataloguing, mounting, answering correspondence. He lived here with me for the two weeks he was in my employ.” Beninson grinned deprecatingly. “You see, I’m a bachelor—live in this big shack all alone. I was really glad of his company, although he was a queer one.”

  “A queer one?”

  “Well,” said Beninson, “he was a retiring sort of creature. Had very few personal belongings, and I found those gone two days ago. He didn’t seem to like people, either. He always went to his own room when friends of mine or collectors called, as if he didn’t want to mix with company.”

  “Then there isn’t any one else who might be able to supplement description of him?”

  “Unfortunately, no. He was a fairly tall man, well advanced in age, I should say. But then his dark glasses and heavy black mustache would make him stand out anywhere.”

  Ellery sprawled his long figure over the chair, slumping on his spine. “I’m most interested in the man’s habits, Mr. Beninson. Individual idiosyncrasies are often the innocent means by which criminals are apprehended, as the good Sergeant here will tell you. Please think hard. Didn’t the man exhibit any oddities of habit?”

  Beninson pursed his lips with anxious concentration. His face brightened. “By George, yes! He was a snuff-taker.”

  Ellery and Sergeant Velie looked at each other. “That’s interesting,” said Ellery with a smile. “So is my father—Inspector Queen, you know—and I’ve had the dubious pleasure of watching a snuff-taker’s gyrations ever since my childhood. Planck inhaled snuff regularly?”

  “I shouldn’t say that exactly, Mr. Queen,” replied Beninson with a frown. “In fact, in the two weeks he was with me I saw him take snuff only once, and I invariably spent all day with him working in this room. It was last week; I happened to go out for a few moments, and when I returned I saw him holding a carved little box, sniffing from a pinch of something between his fingers. He put the box away quickly, as if he didn’t want me to see it—although I didn’t care, lord knows, so long as he didn’t smoke in here. I’ve had one fire from a careless assistant’s cigaret, and I don’t want another.”

  Ellery’s face had come alive. He sat up straight and began to finger his pince-nez eyeglasses studiously. “You didn’t know the man’s address, I suppose?” he asked slowly.

  “No, I did not. I’m afraid I took him on without the proper precautions.” The collector sighed. “I’m fortunate that he didn’t steal anything from me. My collection is worth a lot of money.”

  “No doubt,” said Ellery in a pleasant voice. He rose. “May I use your telephone, Mr. Beninson?”

  “Surely.”

  Ellery consulted a telephone directory and made several calls, speaking in tones so low that neither Beninson nor Sergeant Velie could hear what he was saying. When he put down the instrument he said: “If you can spare a half-hour, Mr. Beninson, I’d like to have you take a little jaunt with us downtown.”

  Beninson seemed astonished; but he smiled, said: “I’d be delighted,” and reached for his coat.

  Ellery commandeered a taxicab outside, and the three men were driven to Forty-ninth Street. He excused himself when they got out before the little bookshop, hurried inside, and came out after a moment with old Uneker, who locked his door with shaking fingers.

  In the Ulm brother’s office they found Heffley, the insurance man, and Hazlitt, Uneker’s customer, waiting for them. “Glad you could come,” said Ellery cheerfully to both men. “Good afternoon, Mr. Ulm. A little conference, and I think we’ll have this business cleared up to the Queen’s taste. Ha, ha!”

  Friederich Ulm scratched his head; Albert Ulm, sitting in a corner with his hatchet-knees jack-knifed, his green shade over his eyes, nodded.

  “We’ll have to wait,” said Ellery. “I’ve asked Mr. Peters and Mr. Hinchman to come, too. Suppose we sit down?”

  They were silent for the most part, and not a little uneasy. No one spoke as Ellery strolled about the office, examining the rare stamps in their wall-cases with open curiosity, whistling softly to himself. Sergeant Velie eyed him doubtfully. Then the door opened, and Hinchman and Peters appeared together. They stopped short at the threshold, looked at each other, shrugged, and walked in. Hinchman was scowling.

  “What’s the idea, Mr. Queen?” he said. “I’m a busy man.”

  “A not unique condition,” smiled Ellery. “Ah, Mr. Peters, good day. Introductions, I think, are not entirely called for…Sit down, gentlemen!” he said in a sharper voice, and they sat down.

  The door opened and a small, gray, birdlike little man peered in at them. Sergeant Velie looked astounded, and Ellery nodded gaily. “Come in, dad, come in! You’re just in time for the first act.”

  Inspector Richard Queen cocked his little squirrel’s head, looked at the assembled company shrewdly, and closed the door behind him. “What the devil is the idea of the call, son?”

  “Nothing very exciting. Not a murder, or anything in your line. But it may interest you. Gentlemen, Inspector Queen.”

  The Inspector grunted, sat down, took out his old brown snuff-box, and inhaled with the voluptuous gasp of long practice.

  Ellery stood serenely in the hub of the circle of chairs, looking down at curious faces. “The theft of the one-penny black, as you inveterate stamp-fiends call it,” he began, “presented a not uninteresting problem. I say ‘presented’ advisedly. For the case is solved.”

  “Is this that business of the stamp robbery I was hearing about down at Headquarters?” asked the Inspector.

  “Yes.”

  “Solved?” asked Beninson. “I don’t think I understand, Mr. Queen. Have you found Planck?”

  Ellery waved his arm negligently. “I was never too sanguine of catching Mr. William Planck, as such. You see, he wore tinted spectacles and black mustachios. Now, any one familiar with the science of crime-detection will tell you that the average person identifies faces by superficial details. A black mustache catches the eye. Tinted glasses impress the memory. In fact, Mr. Hazlitt here, who from Uneker’s description is a man of poor observational powers, recalled even after seeing his assailant in dim street-light that the man wore a black mustache and tinted glasses. But this is all fundamental and not even particularly smart. It was reasonable to assume that Planck wanted these special facial characteristics to be remembered. I was convinced that he had disguised himself, that the mustache was probably a false one, and that ordinarily he does not wear tinted glasses.”

  They all nodded.

  “This was the first and simplest of the three psychological sign-posts to the culprit.” Ellery smiled and turned suddenly to the Inspector. “Dad, you’re an old snuff-addict. How many times a day do you stuff that unholy brown dust up your nostrils?”

  The Inspector blinked. “Oh, every half-hour or so. Sometimes as often as you smoke cigarets.”

  “Precisely. Now, Mr. Beninson told me that in the two weeks during which Planck stayed at his house, and despite the fact that Mr. Beninson worked side by side with the man every day, he saw Planck take snuff only once. Please observe that here we have a most enlightening and suggestive fact.”

  From the blankness of their faces it was apparent that, far from seeing light, their minds on this point were in total darkness. There was one exception—the Inspector; he nodded, shifted in his chair, and coolly began to study the faces about him.

  Ellery lit a cigaret. “Very well,” he said, expelling little puffs of smoke, “there you have the second psychological factor. The third was this: Planck, in a fairly public place, bashes Mr. Friederich Ulm over the face with the robust intention of stealing a valuable stamp. Any thief under the circumstances would desire speed above all things. Mr. Ulm was only half-stunned—he might come to and make an outcry; a customer might walk in; Mr. Albert Ulm might return unexpectedly—”

  “Just a moment, son,” said the Inspector. “I understand there are two of the stamp thingamajigs in existence. I’d like to see the one that’s still here.”

  Ellery nodded. “Would one of you gentlemen please get the stamp?”

  Friederich Ulm rose, pottered over to the safe, tinkered with the dials, opened the steel door, fussed about the interior a moment, and came back with the leather case containing the second one-penny black. The Inspector examined the thick little scrap curiously; a thirty-thousand-dollar bit of old paper was as awesome to him as to Ellery.

  He almost dropped it when he heard Ellery say to Sergeant Velie: “Sergeant, may I borrow your revolver?”

  Velie’s massive jaw see-sawed as he fumbled in his hip pocket and produced a long-barreled police revolver. Ellery took it and hefted it thoughtfully. Then his fingers closed about the butt and he walked over to the rifled cabinet in the middle of the room.

  “Please observe, gentlemen—to expand my third point—that in order to open this cabinet Planck used an iron bar; and that in prying up the lid he found it necessary to insert the bar between the lid and the front wall four times, as the four marks under the lid indicate.

  “Now, as you can see, the cabinet is covered with thin glass. Moreover, it was locked, and the one-penny black was in this closed leather case inside. Planck stood about here, I should judge, and mark that the iron bar was in his hand. What would you gentlemen expect a thief, working against time, to do under these circumstances?”

  They stared. The Inspector’s mouth tightened; and a grin began to spread over the expanse of Sergeant Velie’s face.

  “But it’s so clear,” said Ellery. “Visualize it. I’m Planck. The revolver in my hand is an iron ‘jimmy.’ I’m standing over the cabinet…” His eyes gleamed behind the pince-nez, and he raised the revolver high over his head. And then, deliberately, he began to bring the steel barrel down on the thin sheeting of glass atop the cabinet. There was a scream from Albert Ulm, and Friederich Ulm half-rose, glaring. Ellery’s hand stopped a half-inch from the glass.

  “Don’t break that glass, you fool!” shouted the green-shaded dealer. “You’ll only—”

  He leaped forward and stood before the cabinet, trembling arms outspread as if to protect the case and its contents. Ellery grinned and prodded the man’s palpitating belly with the muzzle of the revolver. “I’m glad you stopped me, Mr. Ulm. Put your hands up. Quickly!”

  “Why—why, what do you mean?” gasped Albert Ulm, raising his arms with frantic rapidity.

  “I mean,” said Ellery gently, “that you’re William Planck, and that brother Friederich is your accomplice!”

  The brothers Ulm sat trembling in their chairs, and Sergeant Velie stood over them with a nasty smile. Albert Ulm had gone to pieces; he was quivering like an aspen-leaf in high wind.