Corbett glimpsed the annoyance on Branwood's saturnine face.

'What does the physician mean, Sir Peter?'

'The night Sir Eustace died, we had been dining at table in the hall. I left after Sir Eustace. Later I returned for a half-finished cup of wine. I drank it but the taste was acrid so I threw it away. After I retired I began to retch and vomit. I spent the night in the latrines. My bowels had turned to water.' Sir Peter cleared his throat. 'The next morning I felt weak. I thought it was something I had eaten until Sir Eustace's corpse was found when I consulted Physician Maigret.'

'He had been poisoned,' the doctor declared triumphantly, as if daring anyone to contradict him.

'With what?' Corbett asked.

'I don't know, but if Sir Peter had finished that cup of wine he would surely have died. I told him to fast for twenty-four hours and drink as much water from the castle well as possible.'

Corbett stared round the group. 'You did say someone was waiting for us?'

'Ah, yes, the two guards and Lecroix are in the small hall.'

'The same two who guarded Sir Eustace's chamber?' 'Of course.'

'Then we had better not keep them waiting. And I would like everyone,' Corbett continued, 'to be present at the interrogation.'

They went back into the castle and into the small hall. Corbett noticed this too shared the general air of decay which hung over the whole castle. A dirty, flagstoned room, its narrow windows were protected by wooden shutters or a few glazed with horn. Along the hammer-beam roof Corbett glimpsed huge cobwebs and on the dirty white-washed walls hung dusty shields bearing the faded escutcheons of former sheriffs. The fireplace was battered and the grate still full of last winter's ash. There were no carpets or rugs on the floor which was instead thickly covered with lime.