"You must hope your coroner and magistrate work quickly then," I said, pretending not to guess at his meaning.

"That is the thing-they do not. And they lack the subtlety to comprehend a crime of this nature. I fear they would blunder into corners of college life that would seem curious to all except men of learning, like ourselves. Whereas you-" He let his implication hang in the air, regarding me with an expression of wary hope.

"I, sir?" I raised my eyebrows with exaggerated surprise. "A foreigner? A Catholic? A man reported to practise magic, who openly believes the earth goes around the sun?"

Underhill lowered his eyes, and released his grip on my arms. "I beg your forgiveness for my hasty words, Doctor Bruno. Fear breeds such prejudices, and we are a fearful nation in these times. And now this fear visits us even in this sanctum of learning…" His voice died away and he looked helplessly toward the far window, away from Coverdale's corpse.

"Are you asking my help in finding this killer?" I asked briskly.

He turned to me, a faint hope in his small, watery eyes. "In ordinary circumstances, I would not think of imposing on a guest-but it seems this killer wants you involved. The papers you showed me-I thought someone was making sport with you, but with this"-he raised a hand again behind him toward the body-"perhaps you can draw him out before there is any more blood spilled."

"Then you believe he will find more victims?" I said, perhaps too sharply.

He turned to me and blinked rapidly, shaking his head. "I only meant-because it seems clear we are dealing with a fiend who is either possessed or mad-"

Just at that moment, there was a scrape and a dull thud from behind us; from the corner of my eye I glimpsed a sudden movement and whipped around to see Coverdale jerk and shift position. The rector shrieked and grabbed my arm again; I heard myself gasp, and for one hideous moment a cold dread washed through me as I wondered if he was not yet dead and had been hanging there in mortal agony all this time. But as I steadied my breathing and took a hesitant step forward, I realised that the knot in the rope holding him to the sconce had begun to slip.

"It's all right, Rector Underhill," I said gently. From the juddering of his clasped hands around my arm I could tell that he was experiencing his own delayed shock and could do with some of Cobbett's strong ale himself. "It was only the rope. But we must take the body down."

"Why did he come here in only his underclothes?" the rector wondered softly, still shaking his head as I helped him to sit again on the largest chest.

"Well, it seems clear that he came up here under duress-perhaps his killer surprised him as he was changing," I offered, as something caught my eye by the window. Next to the longbow, a pile of black material had been neatly folded and placed on the floor. I walked over and picked it up; it was a long academic gown, its cut and trim indicating the degree of doctor of divinity, and it was stiff with dried blood, especially on the front and sleeves.

"That is James's gown," Underhill said, turning away.

"I think our killer must have put this on over his own clothes while he carried out the act," I mused. "I had wondered how someone could have walked away through the college with his clothes bespattered with such a quantity of blood as this killing must have made."

Footsteps echoed on the stairs below and a moment later Slythurst appeared carrying a lantern. He glared at me briefly before handing it to the rector, who was still trembling and wringing his hands. I took the lantern before the rector had a chance to drop it and a brief smile flickered across Slythurst's dry lips. The bursar appeared to interpret Underhill's inertia as an invitation to assume responsibility for the situation.

"We must, in the first instance, send for the coroner to remove this body so that the strong room may be cleaned and returned to its proper purpose and the inquest can be carried out so that poor James may have a Christian burial. His family must be notified-I believe he has a brother in the Fens somewhere, is that not so, Rector?" On receiving no answer, he continued as if he had not expected one. "And I think it would be politic when we announce the death to give out that he was attacked by an unknown thief trying to break into the strong room-we do not want the students indulging in any more idle speculation." He shot me a warning glance.

"That is wise, Walter," said the rector, turning his attention back to Slythurst with a distant, puzzled expression, as if he barely recognised him. "That will give you a little time in hand, won't it, Bruno?" He turned to me with the same look of vague anxiety.

Slythurst snapped his head around. "Time for what?"

"Rector Underhill has asked me to look into the circumstances of the two deaths and see if I can find any connection," I said, returning his stare with a level gaze.

Slythurst's face blanched with fury and his lips almost disappeared.

"With the greatest respect, Rector," he stuttered, choked with indignation, "is that prudent? Doctor Bruno may have a lively imagination, but it can hardly be sensible to involve an outsider"-he pronounced the word with icy scorn-"in a matter which so intimately affects the life of the college. What may come to light…" He paused, eyeing me as a muscle twitched in his cheek, then changed tack. "Besides, he will be gone in a few days."

"He is already involved, Walter," the rector said sorrowfully. "Doctor Bruno received a communication relating to Roger Mercer's death from someone who appears to know something-perhaps even the killer himself."

"Students playing pranks, surely," Slythurst snapped, his eyes darting from the rector to me with undisguised anger. "I would speak to you further about the wisdom of this, Rector-in private."

Underhill nodded wearily. "We will speak, Walter, but first there is much to do and we must work together. Fetch the water-I will clean the wall myself. I want no trace of that left, and I trust that neither of you will mention it? Perhaps you could find a suitable messenger to take a letter to the coroner," he said to Slythurst. "I will go to my library now and write it. Doctor Bruno, how do you wish to proceed?"

I wished the rector had not mentioned my mysterious letter; I still did not trust Slythurst. We had only his word that he collected his papers from the strong room on Saturday evening before the disputation, and I was not sure how much his word was worth, after his deliberate lies over the searching of Roger Mercer's room. If anyone had easy access to the subrector's room and the tower strong room, it was the bursar. Whatever my correspondent knew, the fewer people who learned that he-or she-had tried to share it with me, the better. And now the killer himself wanted this murder explicitly linked to the Catherine Wheel-and the rector wanted that link washed away. I was beginning to feel overwhelmed. The one element that seemed clear was that Coverdale's early exit from the disputation was a key to his murder.

"I would like to find the student who delivered the message to Doctor Coverdale during the disputation, to find out what drew him back to college so urgently."

Underhill nodded. "I will make enquiries. But I beg both of you-say nothing of this to the students until I have the chance to make an announcement at dinner. By then I will try to find a way to explain it with the least alarm-if that is possible."

"Before that, Rector Underhill," I added, "I think I should call on Gabriel Norris. If he delivered his bow and arrows to the strong room as you commanded, we need to learn when, and whether Doctor Coverdale let him in. And I think you should go to your study, take a large glass of your strongest drink, and gather your thoughts for a moment before you decide what to do next."