Holmes and Watson are in an unnamed university town when they are approached by a tutor who wants Holmes to discreetly investigate the theft of the proofs for an exam scheduled for the next morning. If the culprit isn’t found, the exam will have to be postponed, bringing disrepute to the college. The prime suspects are the three students who live in the same building. This isn’t one of Holmes’s best showings, maybe because he’s out of his familiar Baker Street territory, but I did enjoy the academic setting. I have a fondness for mysteries set in schools and colleges. ( )

In this story, Sherlock Holmes finds himself in a famous university town (probably either Oxford or Cambridge) when a tutor and lecturer of St Luke's College, Mr. Hilton Soames, brings him an interesting problem. Someone had been into Soames’s office and looked at the galley proofs of an exam he was going to give. Soames had gone to a friend’s for tea and locked his office. When he came back an hour later, he found a key in the lock. His servant, Bannister, forgot his key after he found Soames was gone for tea. Nevertheless, the proofs were found out of place, with one near the window, another on the floor, and the last still on the desk. Bannister swears that he did not touch the papers. Interestingly, Holmes can tell Soames which of the papers was in which place.
Soames’s desire is to uncover the cheater and prevent him from taking the exam, since it is for a sizeable scholarship. Fortunately there are only three students who will take the exam, all of which live above him in the same building.
Soames found other clues in his office: pencil shavings, a broken pencil lead, a clean, new cut in his new desk surface about three inches (7.5 cm) long, and a small hollow pyramidal blob of black clay speckled with sawdust. He could find no footmarks or other physical evidence.
Daulat Ras, one of the three students, had been to see Soames while the proofs were on his desk, but as far as Soames can recall, they were rolled up and likely would not have been recognizable as such. At Holmes' request,. Soames gives a brief outline of each of the three students. The first, Giles Gilchrist, is an athletic industrious scholar (in contrast to his father who squandered his fortune in horse racing); the second, Ras, is described as quiet and methodical; the third is Miles McLaren, a gifted man but thoroughly dissolute and given to gambling.
Holmes examines the office window from outside, standing on tiptoes to look in. Inside, there are no clues in the carpet. The cheater obviously took the papers over to the window one by one so that he could see Soames returning, but as it happens, he did not come back the usual way. When Soames came in, he was not aware of any hurried footsteps.
Holmes examines the blob of clay, and pays particular attention to the cut in the desk. This then leads him to ask where a nearby door leads. It is Soames’s bedroom. Upon examining that, Holmes finds another, similar, sawdust-speckled blob of clay. Then, he stuns Soames by telling him that the cheater, upon hearing his approach, hid in Soames’s bedroom. He was there, hiding behind a curtain, all the time that Soames was questioning Bannister.
Holmes questions Bannister and is apparently interested in the fact that anyone in the room could have got out after having entered with the key. He also asks Bannister why he sat several chairs away when he suddenly felt unwell at what had happened. Bannister will not venture a hypothesis as to a suspect.
Holmes decides to call on all three students. In Gilchrist’s room on the first floor, and Ras’s room on the second, Holmes cleverly contrives a ruse which will make it necessary for him to borrow a pencil, and a knife to sharpen his own. In neither case was there a promising clue to match evidence found in Soames’s room.
On the third floor, Miles McLaren is rude and will not let anyone in. Curiously, Holmes then asks Soames how tall McLaren is. Soames reckons McLaren’s height is about five foot six (165 cm), making him taller than Ras but much shorter than Gilchrist, who is quite tall, being a hurdler and a long-jumper.
Holmes has now deduced almost everything — all but Bannister’s rôle in this business.
The next morning, the day of the exam, Holmes surprises Dr. Watson by showing him a third, identical, blob of clay. Holmes now knows everything. He confronts Bannister with the evidence. Bannister will not own up to anything, and insists that there was no-one in Soames’s office while he was there. Holmes, however, sends for Gilchrist, and proceeds to lay out his results.
The cheater was someone who knew the exam proofs were there. This could only be Gilchrist because the proofs’ whereabouts had been kept secret, and Gilchrist was the only one tall enough to have been able to look in through Soames’s window to see them there. Holmes has also identified the blobs as the special clay found in the long-jump pit, which is where the third one came from, further implicating Gilchrist. Gilchrist does not help his own position very much by reproaching Bannister for his apparent treachery. Bannister was indeed the one who covered for Gilchrist. He felt that he had to, for old times’ sake: Bannister was once Gilchrist’s father’s butler.
Other clues point to the solution:
The scratch on the desk was caused by Gilchrist’s spiked jumping shoes as he grabbed them in his haste; the scratch naturally pointed towards the bedroom, where he ran and hid;
Bannister had sat several chairs away to hide Gilchrist’s gloves, left on that chair;
Bannister was the one who let Gilchrist out of the now-locked room once Soames had left.
For his part, Gilchrist credits Bannister with convincing him not to profit from his misdeed, and presents Soames with a letter stating his wish not to sit the exam, but accept an offer in South Africa for the Rhodesian Police.
Excellent plot, I recommend this book to all readers that appreciate a very well written mystery. ( )