Time and again he takes me with him to sit over the body of some man, woman or child pitifully slain. 'Is it murder, suicide or an accident?' he asks and so the dreadful stories begin. Often death results from stupidity: a woman forgets how dangerous it is for a child to play out in the cobbled streets, dancing between the hooves of iron-shod horses or the creaking wheels of huge carts as they bring their produce up from the river; still a child is slain, the little body crushed, bruised and marked, while the young soul goes out to meet its Christ. But, Reverend Father, there are more dreadful deaths. Men drunk in taverns, their bellies awash with cheap ale, their souls dead and black as the deepest night as they lurch at each other with sword, dagger or club. I always keep a faithful record.

Yet, every word I hear, every sentence I write, every time I visit the scene of the murder, I go back to that bloody field fighting for Edward the Black Prince. I, a novice monk, who broke his vows to God and took his younger brother off to war. Every night I dream of that battle, the press of steel-clad men, the lowered pikes, the screams and shouts. Each time the nightmare goes like a mist clearing above the river, leaving only me kneeling beside the corpse of my dead brother, screaming into the darkness for his soul to return. I know, Reverend Father, it never will. Athelstan scrutinised the words he had written, replaced the quill beside his letter and walked back to the chancel screen. He looked across as Bonaventure rose and stretched elegantly.

'I intend no offence, Bonaventure,' he said. 'I mean, Sir John, despite his portly frame, that plum-red face, balding pate and watery eye, is, you will agree, at heart a good man. An honest official, a rare fellow indeed who does not take bribes but searches for the truth, ever patient in declaring the real cause of death. But why must I always be with him?'

Athelstan went back to sit before the rood screen. What use was it to list the terrible murders and scenes of violence he had witnessed? What would Father Prior know of them? Souls sent out into the dark before their time, unprepared and unshriven. Men with their eyes gouged out, their throats cut, their genitals ripped off. Women crushed beneath scaffolding or horribly murdered in some stinking alleyway. If Christ came to London, Athelstan thought, he would surely cross to Southwark, where poverty and crime sat like two ugly brothers or wandered the streets hand-in- hand spreading their stench. Bonaventure rose and padded gently over to him. Athelstan stared down at the cat.

'Perhaps I should tell Father Prior about you, Bonaventure,' he said, admiring the sleek black body of the alley cat which he had adopted, noting the white mask and paws, the tattered ear, the half-closed eye.

'You're a mercenary,' he continued, stroking the cat gently on the top of its head. 'But my most faithful parishioner. For a dish of milk and a few scraps of fish you will sit patiently whilst I talk to you, and be most attentive during Mass.'

Athelstan jumped as he heard a sound behind him. He looked round the chancel screen and realised how dark it was in the church, the only light being that from a taper lit before the statue of the Madonna. He yawned. He had not slept the previous evening. He did not like to close his eyes on dreams where he saw his brother's marble-white and glassy face, the eyes always staring at him. So, instead, he had climbed to the top of the church tower to observe the stars, for the movements of the heavens had fascinated him ever since he had begun studying them in Prior Bacon's observatory on Folly Bridge at Oxford. He had been tired and slightly fearful as well, for Godric, a well-known murderer and assassin, had begged for sanctuary in the church. Since his arrival Godric had lain curled up like a dog in the corner of the sanctuary, sleeping off his exhaustion. He had eaten Athelstan's supper, pronounced himself well and settled down to a good night's sleep. 'How is it?' Athelstan murmured, that such men can sleep so well?' Godric had slain a man, struck him down in the market place, taken his purse and fled. He had hoped to escape but had had the misfortune to encounter a group of city officials and their retainers who had raised the 'Hue and Cry' and pursued him to St Erconwald's. Athelstan had been trying to repair the chancel screen and let him in after he hammered on the door. Godric had brushed past him, gasping, waving the dagger still bloody from his crime, and ran up the nave, shouting: 'Sanctuary! Sanctuary!' The pursuing officials had not come into the church though they expected Athelstan, as clerk to Sir John Cranston, to hand Godric over. Athelstan had refused.

'This is God's house!' he'd shouted. 'Protected by Holy Mother Church and the King's decree!'

So they had left him and Godric alone although they had placed a guard on the door and swore they would kill the murderer if he attempted to escape. Athelstan peered through the darkness. Godric still lay sleeping.

Athelstan prepared the altar for Mass, laying out the rather tattered missal and two candlesticks so bent they could hardly stand straight. A chipped, silver-gilt chalice, paten and small glass cruets, containing water and wine, were placed on the spotless altar cloth. Athelstan went into the dank sacristy, put on the alb and scarlet cope, crossed himself and went out to begin the magic of the Mass, priest before God, offering Christ to the Father under the appearances of bread and wine. Athelstan blessed himself as he intoned the introductory psalm.

'I will go into the altar of God, unto God who gives joy to my youth.'

Godric snored on, oblivious to the drama being enacted a few yards away. Bonaventure sidled up to the foot of the altar steps. The cat licked its lips, swishing its long tail in anticipation of a deep bowl of creamy milk as his reward for attention and patience. Athelstan, now caught up by the music of the words of the Mass, swept through the readings of the Epistle and the Gospel, reaching the Offertory where he mingled the water and wine. At the far end of the church a door opened and a hooded figure slipped in, moving soundlessly up the darkened nave to kneel beside Bonaventure at the foot of the steps. Athelstan forced himself to keep his eyes down on the white circle of bread over which he had breathed the words of consecration, transforming it into the body of Christ. The consecration over, he intoned the Lord's Prayer: 'Pater Noster, qui est in caelis.'

His voice rang loud and clear through the hollow nave. He paused, as the canon of the Mass dictated, to pray for the dead. He remembered Fulke the warrener, a member of his parish killed in a tavern brawl four nights earlier. Then Athelstan's own parents and his brother Francis… the friar closed his eyes against the hot tears welling there as the faces of his family appeared, clear and distinct in his mind's eye.

'God grant them eternal rest,' he whispered.

He stood swaying against the altar, wondering for the hundredth time why he felt like an assassin. Oh, in France he had killed men whilst fighting for the Black Prince, the old king's eldest son, who wanted to unite the crowns of France and Castille with that of England. Athelstan had shot arrows as good and true as the rest. He remembered the corpse of a young French knight, his cornflower blue eyes gazing sightlessly up at the sky, his blond hair framing his face like a halo, Athelstan's barbed arrow embedded deeply in his throat between helmet and gorget. The friar prayed for this unknown knight yet he felt no guilt. This was war and the Church taught that war was part of man's sinful condition, the legacy of Adam's revolt.

'Oh, God, am I a murderer?' he whispered to himself.

Athelstan thought once again how, as a novice in Black- friars, near the western wall of the city, he had broken his vows and fled back to his father's farm in Sussex. His mind had been filled with dreams of war and he had encouraged his younger brother in similar fantasies. They had joined one of those merry bands of archers who swung along the sunny, dusty lanes of Sussex down to Dover and across a shimmering sea, to reap glory in the green fields of France. His brother had been killed and Athelstan had brought the grim news back to the red-tiled Sussex farm. His parents had died of sheer grief. Athelstan had returned to Black- friars to lie on the cold flagstoned floor of the Chapter House. He had confessed his sin, begged for absolution, and dedicated his life to God as reparation for the grievous sins he had committed.