‘Quite so,’ Cranston declared from where he stood near the door. ‘The Crown’s lawyers would have spun a fine tangled trap of treason.’

‘Richer turned to you, Master Crispin,’ Athelstan continued. ‘Only God and you know what was offered: a huge bribe, freedom to settle down quietly in France, not to mention the opportunity of exacting revenge on your hard-hearted master who apparently no longer cared for you? Oh, Richer was cunning and devious. He would smear all that with righteousness. He would argue how Sir Robert should be rightfully punished for his share in what had happened. You, Crispin, would not only be the divine instrument for that but also do great good. You would return the bloodstone to its rightful home. Unbeknown to Sir Robert, you and Richer secretly plotted his murder.’

‘Murder?’ Crispin protested. ‘Me, how can I buy poisons?’

‘I never said you did. Richer gave them to you. He was sub-prior in an abbey where the abbot was lost in his own concerns, where the prior was pliable as soft clay in the potter’s hands. St Fulcher’s is a treasure house of potions and powders. Either on the eve of St Damasus when he visited here or sometime before, Richer handed over these poisons to you: hemlock, henbane, nightshade or the juice of almond seed, perhaps all four. You certainly knew their properties.’

‘I do not.’

‘Yes, you do. I have studied the muniments at St Fulcher’s. You are left-handed, Crispin, a matter I shall return to. When you were a novice, the master was frustrated by this, he would not allow you to work in the library, scriptorium or chancery so you became an assistant to the abbey apothecary.’

Crispin, all agitated, his face ashen and drawn, could only shake his head.

‘Now,’ Athelstan persisted, ‘on the eve of St Damasus, the day of his murder, Sir Robert entertained Prior Alexander and Richer. He met you all in the solar?’

Alesia nodded, all watchful.

‘He put the Passio Christi back into its casket and returned here to his chancery chamber.’

‘Yes,’ Alesia replied. ‘Crispin, you went with him.’

‘How long were your father and Crispin absent?’

‘Not for very long, we were all preparing for supper.’

‘Precisely,’ Athelstan replied. ‘However, back in his chamber, Sir Robert was preparing to lock the bloodstone away. You, Crispin, intervened. You have read the “Liber”. You knew about the recuperative powers of the Passio Christi, especially round the Feast of St Damasus. How someone inflicted with a disease of the eyes should hold the precious bloodstone against their head? The “Liber” lists all such practices. You, Crispin, begged Sir Robert for such an opportunity to hold the precious relic against your own eyes. You pleaded as a loyal and faithful servant for help from the bloodstone. I am sure Richer coaxed you to ask and, perhaps, Sir Robert to consent. You may well have asked for this before. I am sure you did and your master agreed. On that particular evening you would point out that the bloodstone might soon pass from your master’s hands to others who might not be so obliging. Sir Robert approved. He gave it to you in trust for the night. You would, and he agreed, ask for the matter to be kept confidential. You took the Passio Christi and Sir Robert simply locked the coffer. Why should he object? In the morning the bloodstone would be returned by his faithful servant. Crispin certainly wouldn’t tell anybody. Neither would Sir Robert — why should he? You all adjourned for supper.’ Athelstan paused. ‘However, Crispin, you had planned a subtle death for your master. He would not survive the night to ask for the bloodstone back.’ Athelstan lifted the writing tray, gesturing at the quill pens. ‘I’ve studied your master. He was right-handed. He constantly nibbled at the quill plume. You prepared the pens left in this tray that night. You coated their plumes with the poison at your disposal; they were richly drenched in some noxious potion. Sir Robert would, as he was accustomed, nibble and chew at the quill plumes. He would absorb the poisons, small tinctures at a time but the mixture would, over hours, wreak their effect.’ Athelstan picked up a quill pen lying on the writing palette. ‘This is the proof. You thought you were safe, Master Crispin. You did not care. You had removed the poisonous quill pens you’d first laid here but, in fact, you were sealing in your own guilt. You made one miscalculation: the arrival of Sir John and myself. This chamber was secured. You could not rectify any omission.’ Athelstan held up the three quill pens for all to see. ‘Are these nibbled and chewed? No. More importantly, Crispin, you are left-handed. I am right-handed, I hold the quill such and the point on the right side of the pen becomes worn, yes? These, however, have been used by a left-handed writer.’ Athelstan turned all three quill pens, tapping their worn edges.

‘Sir Robert,’ he added. ‘Even when he was in the novitiate he was known for chewing the end of his pens. He laughingly referred to this, Crispin, when you and he were once strolling up the south aisle of St Fulcher’s abbey church. You were overheard by the anchorite who shelters there. Mistress Alesia, did you not tell me the same?’

‘It’s true,’ Alesia whispered, ‘my father always chewed the ends of his pens, a mannerism he couldn’t give up despite my scolding.’

Others murmured their assent. Crispin undid the cord of his cambric shirt as if he couldn’t breathe properly.

‘But we all came in here that morning,’ Lady Helen demanded. ‘Nobody moved anything, I am sure.’

‘Are you?’ Athelstan replied. ‘Look, Crispin is Sir Robert’s clerk. He has an ink horn and quills strapped to his belt. It’s one of the first things I noticed about him.’

‘He always carries pens,’ Alesia declared, ‘he always has ever since I can remember.’

‘It was the same that morning,’ Athelstan agreed. ‘You all came in here. You were distraught and distracted. Crispin, the faithful clerk, moved to Sir Robert’s desk. Why shouldn’t he rearrange the pens? He makes the exchange in the twinkling of an eye. He leaves these quills, the ones he has used himself, and takes the poisoned ones which, I am sure, he immediately burnt.’ Athelstan paused, letting the silence deepen.

‘But surely,’ Lady Helen now spoke directly to Athelstan, ‘he must have realized the mistakes he had made?’ She paused. ‘Of course.’ She answered her own question. ‘It was too late. Crispin never expected, as you said, this chamber to be sealed with all the evidence in it.’

‘Crispin’s eyesight is also poor,’ Athelstan declared. ‘He may have failed to realize the full implications of what he’d done. Once Sir Robert’s corpse was discovered, he was committed to the heinous lie he had to live. Perhaps he delayed gnawing on the ends of the replacement quill pens until it was too late. Or did he panic, frightened that one of you would note such an act so closely associated with his master rather than himself? What he’d done was certainly settled by this chamber being sealed. However,’ Athelstan pointed to the ashen-faced clerk, ‘only he can say. But remember, for Crispin, Sir Robert’s death was only a means, a device to get his hands on the bloodstone and keep it.’

‘It must be true,’ Kinsman Adam whispered. ‘Sir Robert would only have entrusted the Passio Christi to someone in this room, someone he trusted implicitly, there’s no other explanation.’

‘Don’t accuse me!’

‘I do, Crispin,’ Athelstan declared. ‘True, I do not have full proof but I possess enough to present a bill of indictment. You’ll be arrested and lodged in Newgate. The Regent’s torturers will demand your presence at the Tower. They’ll interrogate you day in and day out. They will not let you die, though there’ll be times when you pray that they do so. Confession or not, you’ll be judged a traitor for having stolen Crown property. You will also be condemned as sacrilegious and excommunicate because the Passio Christi is a sacred relic.’ Athelstan held Crispin’s terrified gaze. ‘In the end you’ll suffer the full penalty for treason. You’ll be drawn on a hurdle from the Tower to the Elms at Smithfield. You’ll be half hanged, disembowelled and castrated. You will die the enemy of both church and realm. You’ll never be allowed to enjoy the fruits of your foul act.’