Prince of Darkness

who weren't watching precise times, that at the very moment you were in the church, the Lady Eleanor was still alive.
    'Of course, you made another mistake, didn't you? You were hoping that Dame Martha, like everyone else, saw what you wanted them to see: a woman wearing Lady Eleanor's cloak and ring must be Lady Eleanor. But the old nun was sharp. When you waved your hand, the huge sapphire ring flashed in the sunlight. Poor-sighted as they were, they caught the brilliant light of the jewel, but you had mistakenly put it on your left hand, whereas Lady Eleanor always wore the ring on the right. The old nun remembered this, hence her constant little riddle: "Sinistra non dextra" – "on the left, not the right". She could not understand it.'
    Agatha drew a little closer. Corbett noted she had lost some of her arrogance and was more watchful. She kept squarely in front of him, as if trying to block his view of what might be happening behind her.
    'Let us say,' she replied quietly, 'that it happened as you described. I admit a cloak would not be missed, but a precious ring? Remember, the Lady Prioress found the corpse at the bottom of the stairs!'
    'Of course you know that's a lie! The Lady Prioress, anxious about the whereabouts of the Lady Eleanor, left the refectory and went back to the darkened convent building. They found Lady Eleanor dead in her chamber and, concerned about the possible consequences, took her body to the foot of the stairs to make it look like an accident. It was dark, they were frightened, and would not notice the ring was missing. If anyone did, the logical explanation was that it had fallen off. Of course, they sent for you to help take the corpse back up to the chamber. That's when you thrust the ring back on to the dead woman's finger.' Corbett paused. 'Most subtle,' he added. 'You knew Lady Amelia would find the corpse and, for the good name of Godstowe, try to disguise Lady Eleanor's death as an accident You, an assassin, cleverly used innocent nuns such as Lady Amelia and Dame Martha to protect yourself. Whether they liked it or not, they became your accomplices; Lady Eleanor's death was made so confusing, no one would ever discover the truth.'
    Corbett, now concerned by the smiling malevolence which confronted him, pulled the dagger from its sheath.
    'That,' he continued, 'would have been the end of the matter, but Dame Martha had to chatter and threaten to talk to the Lady Prioress. Did you understand her riddle?'
    Agatha smiled.
    'You found killing her easy,' Corbett continued. 'Old Martha prepared a bath. She put up a screen and locked her chamber door. You, the ever caring sister, came along, probably with a bar of soap. The old nun gets out of the bath, leaving a trail of water on the floor as she unlocks the door. You give her the soap, chattering merrily as Dame Martha goes behind the screen back into the tub. She was an old lady, her death would have been quick. Perhaps you pulled her by the ankles, dragging her head beneath the water? Any sailor would ted you a swift inrush of water to the mouth and nose makes you speedily lose consciousness. You pick up the cake of soap and leave as quietly as you entered.'
    Agatha nodded.
    'Most logical,' she murmured. 'A concise, lucid description.' Her lips parted in a snarl. 'You should have taught at schools at Oxford.'
    'And not come here,' Corbett added quickly. I upset your tittle plans, did I not? But, of course, others unwittingly protected you. Father Reynard, who sent messages to de Craon; Gaveston and his dogs; the Prince of Wales and his infatuation with his favourite. And, of course,' Corbett concluded bitterly, 'our most sovereign lord the King, with his penchant for mystery and secrecy.' Corbett walked towards her. I suppose,' he remarked drily, 'the only good deed you performed was to dissuade Lady Eleanor from taking the powders Gaveston sent her. The royal catamite must have been perplexed.' Agatha smiled.
    'Yes, I did. I watched Gaveston and his meddling tricks. On no account could Lady Eleanor die of poisoning. Such powders might be traced. If the good lady had to die, there had to be no link with the Prince. A nice, subtle mystery which would keep everyone guessing.' She shrugged. 'Naturally, I had to watch de Craon as well.'
    'But the rest?' Corbett asked. 'And the deaths of two nuns? Surely the King ordered none of these?'
    Dame Agatha opened her hand.
    'No dagger, Hugh,' she whispered. 'For what I did was on the King's