‘Such as?’ Athelstan asked.

‘Spying, trading in secrets and, above all, murder. A clerk from the French chancery ostensibly went on pilgrimage to the shrine of the Three Wise Men at Cologne. What he didn’t tell his masters in Paris was that he took certain secrets with him and sold them to the burghers of Cologne. These were trade secrets: information which could allow someone to control the market in wines. Great rivalry exists between the vineyards of France and those of Germany. The clerk was well rewarded. Of course, he couldn’t return to Paris but, on the receipt of his ill-gotten gains, he set himself up in some estate, a pleasant house overlooking Cologne Cathedral. One afternoon he was found swimming in his own carp pond, a garrotte string round his neck. The city council had no proof, but the whisper in the merchant community was that Mercurius had paid this French traitor a house visit.’ Gervase sipped at his wine. ‘Now, Sir Maurice here caused a great stir when he took the St Sulpice and St Denis. The French believed that we had a spy high in their councils. No, no.’ He held out his hand. ‘I must be more precise. They believed that one of the senior officers on board ship was in the pay of the English court.’

‘And is that true?’ Sir John barked.

‘Jack, Jack.’ Gervase shifted his head. ‘You may ask but you know I won’t answer. Suffice to say the French believed that.’

‘And they have sent Mercurius to London?’

‘Precisely: that’s the news our merchant brought.’

‘But there are always French spies in London.’ Cranston’s face showed his annoyance at these subtle, silken treacheries. ‘And a Frenchman is a Frenchman wherever he goes.’

‘I didn’t say he was French,’ Gervase replied. ‘We know a great deal about Mercurius. He’s not French or Gascon but English. A clerk in the Bishop of Norwich’s household, he joined a free company and went to France. He was captured. Now the French have a way with freebooters, they just hang them out of hand. Mercurius, whose real name was Richard Stillingbourne, entered into a deal with his new masters: in return for his life and a bag of silver he was released. He led the French back to where his free company was quartered and organised their slaughter. Mercurius has a passion and skill for killing as other men do for riding a horse or singing a song. Now, my belief is that the French have sent him into England and that he is responsible for the death of Serriem at Hawkmere.’

‘And so he could be anyone?’ Athelstan asked.

‘He could be one of the parishioners. He might even be Aspinall, the physician. One of the servants, a chapman, a tinker, a guard. He’s a master of disguise. He can appear stooped and aged, the beggar on the corner, or haughty and arrogant.’ Gervase grinned at Sir Maurice. ‘Even the young knight with a falcon on his wrist.’ He spread his hands in mock innocence. ‘Even a humble clerk.’

‘Would de Fontanel know of this?’ Athelstan asked.

Gaunt shook his head. ‘The French envoy has taken a house in Adel Lane; it’s watched day and night. No stranger has approached it:

‘And de Fontanel?’

‘He never goes out.’ Gaunt smirked. ‘He might be frightened. My guard dogs know him, the foppish way he dresses, the ridiculous hat!’

‘He’s only a minor envoy,’ Gervase added. ‘Sent to vex and irritate. Mercurius will answer only to the Chancellor in Paris.’

‘If the French believe,’ Gaunt continued, ‘that there is a traitor among those men at Hawkmere, Mercurius will kill him.’ Gaunt leaned forward, his face drawn with excitement.

For a moment he reminded Athelstan of a wolf he had seen in the Tower, the sharp, pointed face, the hooded, unblinking eyes, the hunched shoulders.

‘I have prayed,’ Gaunt said, ‘that one day, Mercurius will enter our web. The French have whistled up a dance and dance we must but, Sir Jack, Brother Athelstan, and you Master Gervase, I want Mercurius’ head. He is more important than all the ships the French can muster in the Narrow Seas.’

‘But he’s not only here for that, is he?’ Athelstan pointed across at Sir Maurice. ‘They also hold you responsible for the loss of their ships. I am not threatening you,’ Athelstan continued, Gervase now nodding his head. ‘Mercurius could also be in England to kill you.’

‘I agree,’ Gaunt said. ‘But these men at Hawkmere are his real prey.’

‘Why not move the prisoners?’ Sir John asked. ‘Take them out of Hawkmere, up river to the Tower?’

‘It’s tempting,’ Gaunt replied, ‘but I don’t think we’ll achieve much. The capture of Mercurius is important. We have a better opportunity if they are kept in the more, how can I put it, open surroundings of Hawkmere? Moreover, if Mercurius is one of them, it will make little difference. At this point of the dance, the French have it all their own way. If the prisoners die, they’ll appeal to the Pope in Avignon, depict us as breakers of the truth, violaters of the Papal peace. Of course, the murders will continue but the French don’t really care. They hope to kill the traitor. Perhaps make an example of him and, for all I know, slay one of my principal household knights.’ Gaunt sniffed. ‘Mercurius may have slain Vulpina to close her mouth.’ He slapped his leather gauntlets against his thigh. ‘You, Sir Maurice, should be very careful. This business at the Golden Cresset may well be the work of Mercurius. Well, Gervase, now we have Brother Athelstan here, there is one other matter.’

The Master of Secrets looked away and cleared his throat.

‘Ah yes, yes, there is. You know, Brother, the doings of the Great Community of the Realm?’

‘All London does.’

The Master of Secrets undid his white shirt. Athelstan noticed with amusement the hare’s-foot slung on a chain round his throat. Gervase caught his gaze.

‘It’s to ward off the colic,’ he explained, rubbing his stomach.

‘Continue!’ Gaunt ordered harshly. ‘My falcons and dogs await, the day draws on.’

‘I have it on good authority,’ the Master of Secrets went on, ‘that the Great Community of the Realm is very active in Southwark and may well have agents who are members of your parish.’

‘I know nothing of that,’ Athelstan replied quickly.

‘There are many priests, hedge-parsons among its leaders,’ Gaunt intervened silkily. ‘They lard their talk with quotations from the Scriptures on the equality of man.’

‘Then, my lord, they quote most accurately.’

‘In reality,’ Gaunt retorted, ‘they are as devoid of Christ as they are of grace.’

‘In which case, my lord, they have a great deal in common with the people against whom they plot.’

Sir Maurice’s head went down. Sir John’s hand covered his eyes while Gervase looked up at the ceiling as if searching for cobwebs. Gaunt held Athelstan’s gaze.

‘One day, Brother.’ He got to his feet. ‘One day, all of this nonsense will come to a head. I’ll hang every man jack of them!’

‘They are only hungry,’ Athelstan said. ‘They eat hard bread. They give rags, soaked in wine, for their babies to suck. Sometimes in winter the only meal they have is the snot they swallow.’

‘Brother!’ Sir John intervened warningly.

Gaunt’s expression abruptly changed. He smiled and brought his hand down on the little Dominican’s shoulders.

‘Only an honest man speaks the truth, Brother.’ He opened his purse, shook out some silver coins and thrust them into Athelstan’s hand. ‘Buy your poor some bread. Tell them to pray for John of Gaunt.’ He put on his gauntlets. ‘But tell them, if they are caught in arms plotting against the Crown, they’ll hang.’ He walked to the door and turned, his hand on the latch. ‘I set you a hard task, Brother,’ he said quietly. ‘I want you to help Sir Maurice here for he is a man I’d like my own son to grow into. I want these murders stopped. I want to see Mercurius’ head on a pole over London Bridge. Do that and, I swear, the streets of Southwark will run with wine. Now, as I have said, my dogs wait. I bid you adieu.’