Labar had thrown two men to shadow Larry Hughes, not hopefully, but as a matter of precaution. Others were trying to discover if Larry had been in touch with any of the greater artists in burglary of late. Then, again on general principles, the movements of every crook who was big enough in his profession to be possibly involved had to be checked. Any one of these possessed of sudden funds, any one absent from his usual haunts, might be a link in the chain that Labar was trying to establish. Nothing could be taken for granted. Even Gertstein himself--this would have annoyed him--was having some of his private habits pried into, and his associates looked up. The Yard does not despise scientific methods; but here were no bloodstains, no finger-prints, no trivialities from which a high-domed scientist in an easy chair might deduce the name and address of the main culprit. It was a thief taking enterprise in the good old way of the Bow Street runners, differing only by the use of a more complex and more perfect organisation. For a young detective inspector of the Criminal Investigation Department who was under suspicion of slackness it was decidedly not a day for golf. Midnight was very near ere Malone returned to Grape Street. After tracking the manager of the bank to his lair in Golder's Green, he had dragged him back to the bank, and searched out the thousand pound cheque, together with two others unquestionably genuine, for the sake of comparison. "This fellow knows nothing of the circumstances in which it was changed," said Malone. "Suppose we'll have to look up the cashier in the morning on that point." Labar thrust his hand into a desk drawer and pulled out a magnifying glass. Placing the suspected cheque and another in front of him he studied them intently for a few minutes. "Did he hold any views on whether it was a forgery or not, Bill?" he asked without looking up. The other shook his head. "He's a cautious Scot. You see if it is a forgery the bank will be liable. Didn't want me to bring away the cheques at first. Someone had been telephoning him to send back all cancelled cheques to Gertstein early in the morning." Labar abruptly laid down his magnifying glass and stared at his aide-de-camp. "Who was that?" he demanded. A slow grin broke over the usual inexpressive features of Malone. He had an impish delight in sometimes startling his superior. "I thought it would interest you, guv'nor," he said. "He didn't know. The voice was that of a woman, and she said that she was telephoning on behalf of Gertstein." "A woman's voice," repeated the inspector, thoughtfully. He uncoiled his six feet from his chair, and stretched himself. "I'm all in, Bill," he announced. "Let's put up the shutters for the night. Nine o'clock sharp in the morning."