Though the room was neater than the last time I had been there, it had been left in a state of transition, and I felt a sudden pang of loss for James Coverdale, who had barely enjoyed one day as subrector before he met as grisly a fate as his predecessor. I had found little to like about the man, but it was a horrific death to have come knocking on the door of the room that he had coveted for so long, just as he was in the process of unpacking his belongings. Slythurst occupied himself straightaway with the bundles of paper on Coverdale's desk; I did not like this, as I guessed that any clue as to what had happened to Coverdale on Saturday night would probably be found among his documents, and I was about to suggest that we divide the work of looking through the desk, when I noticed a smudged bloodstain almost in the hearth.

Crouching to look closer, I saw that one brick in the fireplace, to the right of the hearth, was slightly out of alignment, protruding from the wall as if it were not joined by mortar. I was just able to grip its sides by my fingertips, though I did not have quite enough purchase to ease it from its place, and as my fingers slipped and I grazed my knuckles, I gave a small cry.

"What have you there?" Slythurst jerked his head up, dropping the book he had been perusing, and rushed to crouch at my side. I licked the blood from my scraped fingers and tried again. With some patience, I gently worked the brick from one side to the other, feeling it give a little more each time as it crunched against the bricks on either side.

"Come on, man!" Slythurst muttered. "Shall I try?"

"I have it," I snapped, and in a few moments the brick was free, revealing a dark cavity built into the side of the fireplace. I thrust in my hand and rummaged as far as I could, but all I felt was the brickwork at the back of the hole. "Nothing," I said, bitterly, sitting back on my heels.

"Out of the way," Slythurst barked, elbowing me roughly to one side. His skinny arm seemed to disappear farther into the recess, but though he seemed determined to prove me wrong, he too withdrew his hand empty. "Devil take him, that whoreson!" he cursed, rubbing his knuckles.

"Well, whoever came this time knew where to look," I said grimly, my knees cracking as I stood. "And it seems he found what he came for."

"To hell with it!" Slythurst spat. He appeared to be taking the discovery of the empty hiding place as a personal injury. I wondered if the cavity in the fireplace had contained whatever Slythurst had been searching for after Roger Mercer's death-it was not a large space but it could easily have concealed a bundle of letters or documents-and if his anger was therefore directed at himself for not having found it on his previous search. But this time there was no sign of a frenzied rummage through Coverdale's belongings; whoever killed Coverdale had evidently known of the loose brick and moved straight to take whatever was hidden there, after first washing Coverdale's blood from his hands. But this could only mean that whoever had searched the tower room before I arrived on Saturday morning, while Roger was still in the garden being savaged by the dog, had not known of the hiding place, and was therefore not the same person who had killed Coverdale. Neither, by this reckoning, could it be Slythurst, unless he was a supremely skilled actor; he was, after all, the only other person who could legitimately demand a key to the subrector's room and no one would be able to confirm or deny the precise time of his departure for Buckinghamshire, or his return.

Slythurst appeared impatient to leave; plainly he had decided that there was nothing more of use to be found.

"I do not see what further purpose we achieve here," he muttered, moving to the door and clinking the keys as if this were a signal that my time was up. "I am needed by the rector, and I must lock this room, so if you have done-"

"Tell me, Master Slythurst," I said, "do you believe our killer has found whatever you yourself were hoping to find here after Roger Mercer's death?"

The look he gave me dripped with contempt. "I don't know what you are talking about. I did not take a key from a man's pocket as he breathed his death rattle, like some," Slythurst said, his face very close to mine so that I could smell the sourness of his breath.

"I only ask, because it would seem that two men have died for whatever was hidden in that hole, and I'm assuming you know what it was," I said.

"One might think that would be warning enough to the over-curious," he replied, with a smile that cut through his thin face like wire. "I must go to the rector. You might do well to get on with finding the owner of the murder weapon. That would seem a useful place to start your enquiries, Doctor Bruno, since you have been good enough to offer the college your services."

As I passed him in the doorway with a last look of disdain, I found myself fervently wishing that Slythurst would prove to be the killer so that I could have the enormous pleasure of seeing that sarcastic sneer wiped from his sallow face, and immediately tried to shake myself free of such dangerous prejudice.

At the foot of the staircase a large, stocky man with almost no neck stood blocking the archway through to the quadrangle; he started when he heard the noise behind him and his hand moved swiftly to his belt. I could not help smiling when I saw he carried some kind of kitchen fork there as a makeshift weapon; this, then, was the guard appointed to keep the tower sealed.

"Peace, Dick," Slythurst said, holding up a hand. The man lowered his head deferentially and moved aside to let us pass into the rain that still fell in steady sheets, splashing from spreading puddles between the flagstones of the courtyard. I pulled my jerkin up around my ears and made to step out into the deluge when three students came running and laughing out of the adjacent staircase, holding their leather satchels over the heads against the weather. I recognised one of them as Lawrence Weston, the boy who had escorted me to the disputation on Saturday evening, and I reached out to accost him.

"Master Weston, I wondered if I may ask your assistance?" I began urgently. He looked somewhat taken aback, and I realised that in my haste I had grabbed hard onto the sleeve of his gown.

"I will help if I can, Doctor Bruno," he said, uneasily, for my manner clearly struck him as out of sorts. "Let us step out of the rain, though." He motioned me back into the shelter of the staircase he had just left. I noticed Slythurst watching our exchange with suspicion; when I caught his eye, he quickly pulled his gown around him and scuttled off toward the rector's lodgings opposite.

"There was a boy, a student," I said to Weston, once we were under shelter, "who delivered a message to Doctor Coverdale during the disputation on Saturday night, that caused him to leave immediately he read it. Do you know who the boy was?"

"How should I know, sir?" he replied, perhaps sounding more ungracious than he had intended, for he then said, "I mean, I could ask around, if it is important."

"Thank you," I said, turning to leave. "There will be a shilling for you if you find him."

Weston looked briefly impressed, and nodded before rejoining his friends. I braced myself to run into the courtyard.