And concerned. The man kept his address a close secret and doubtless for excellent reasons. Joe had no intention of bringing danger within his orbit. He was keeping up his guard. He ambled around the square again, marking his exit, and when he was sure he was unobserved, he slipped off into the rue Mouffetard. A lamp-lighter was moving down the street creating romantic pools of light and Joe hurried to get ahead of him, hugging the shadows. He was looking for a baker’s shop. In the alleyway to the side of it he found a door which opened at his tap.

He was greeted by Bonnefoye who closed and bolted the door behind him. ‘We’ve got him settled in,’ he told Joe as he led the way up a flight of stairs. ‘All’s well! Through here – it’s a bit crowded and you’ll have to share a room with me if you want to give the Ambassador a miss tonight. I gave Sir George our only guest room.’

Sir George was sitting at a kitchen table shelling peas. He was under instruction from a middle-aged woman who, with her striking dark looks, could be no other than Bonnefoye’s mother, and he appeared to be doing well at his task. His manicured thumbnail was slicing along with skill, making short work of the pods. When his mentor turned to greet Joe, he stuffed a podful of peas into his mouth and was sharply rapped on the knuckles.

‘Now add the spring onions and the butter . . . more lettuce leaves on top . . . tiny drop of stock . . . don’t drown it . . . and there you are! Put it on the stove. Back burner . . . So glad to meet you at last, Commander!’ The voice from the telephone. Youthful, bossy and eager. ‘I’m running a little late this evening and I’ve had to call up reinforcements.’ She flashed a devastating smile at George. He grinned and mumbled a greeting across the table, content to take a back seat in the proceedings.

Madame Bonnefoye was much younger than George – perhaps fifty years old but, in the way of Frenchwomen, still attractive. She whisked off her grey pinafore to reveal a black widow’s dress enlivened by a pink scarf draped at the neck. Bonnefoye’s father, he had told Joe, had fallen at Verdun.

‘Jean-Philippe! A glass of wine for the Commander! It’s one from our home village in Burgundy. We bring it back in quantities. You boys have ten minutes to exchange information before you present yourselves at table. It will be a very simple supper: I made some soup to start with, then the butcher had some excellent veal which will be good with George’s petits pois à l’étuvé, followed by cheese and, since Jean-Philippe tells me you Englishmen are fond of sweet things, I’ve got some chocolate éclairs from the pâtissier.’

Joe decided he’d died and gone to heaven and, as he’d always thought it might, heaven smelled of herb soup and rang with a woman’s laughter.

He went to sit in the small salon of the apartment with Jean-Philippe, listening to the chatter from the kitchen. George’s stately but adventurous French sentences rolled out, to be punctuated by sharp bursts of amusement and exclamation from Madame Bonnefoye.

‘First things first,’ said Joe. ‘Security. I’m as sure as I can be I wasn’t followed here. You?’

‘Sure. But we mustn’t reduce the level of precaution. A message came by telephone late this afternoon. From Miss Watkins, I’m afraid. One of my staff took it down and I’ve translated it but I think it’s very clear. All too clear!’ He passed Joe a scrap of paper.

My new boyfriend very keen! He even came shopping with me. Was compelled to go on the offensive. He has a two-inch red scar on his left jaw.

Joe was aghast. He picked out the word which most alarmed him. ‘“Offensive”, she says?’

Bonnefoye cleared his throat. ‘This ties in with a report we had from the Galeries Lafayette,’ he said. ‘To be precise – from the ladies’ underwear department. A customer lodged a complaint against a man she alleged was following and threatening her. Two assistants, who remarked the young lady grappling with a tall man in a dark overcoat, went to her aid and attempted to detain him. Unfortunately he was able to effect an escape.’

‘And the scar? I hardly dare ask!’

‘. . . was already a feature of his physiognomy before he encountered Miss Watkins.’

‘Thank goodness for that! But we should never have involved her.’

‘I agree. And it’s too late now to uninvolve her.’ Bonnefoye sighed. ‘But look – if these people are as good as we think they are, they’ll make enquiries and discover that she has absolutely no connection with Sir George and leave her to get on with her hearty tennis life. They’ll assume that she was just spooked by an over-zealous piece of shadowing. He’ll probably get a ticking off from his boss – should have had more sense than to follow her into the lingerie section. And Miss Watkins has certainly got closer – physically at any rate – to the tool they’re using than we have.’

‘That scar? Any use to us?’

‘Yes, could be. I’ve reported it to the division that keeps our Bertillon records. All marks of that kind are listed, classified and kept on card. If the chap has committed a crime before, his features will be on file and indexed. They ought to be able to come up with a few suggestions.

‘The thing that’s worrying me, Joe, is their apparent preoccupation with Sir G. They seem to have him in their sights. But why? Did he see something he’s not told anyone yet? Does he know something he ought not to know? You’ll have to grill him. I can’t seem to get near him. Any attempt on my part at putting a few questions gets batted aside – with the greatest good humour of course. Genial, avuncular, smelling of roses – and he’s as slippery as a bar of soap. But tell me – how did you get on with the widow?’

After a draught or two of the Chablis he was handed, Joe launched into an account of his evening.

‘She was off to Fouquet’s, eh?’ Bonnefoye was entertained by the thought. ‘I’ll make enquiries. We’ll know tomorrow who she met, what they ate, what time they left and where they went afterwards! Are you thinking – there’s one lady who is delighted that old Somerton was done to death?’

‘She told me she had no idea her husband was in Paris – they hadn’t communicated for years. And, of course, she was hundreds of miles away from the scene of the crime . . .’ Joe began dubiously.

‘Well, if your mad theory about the crime-order-catalogue business is correct, she would be. That’s the whole point of it. They have the telephone in England and the wires run as far as Paris, remember.’

‘Not sure she fits the frame,’ said Joe. ‘Glad enough, yes, to be rid of the old boy. As, indeed, might be the son I discover she has. The one who succeeds to the title. And who knows what else! We might check on him and the size and nature of his inheritance. But why would she or he or they bother with all the palaver? I mean the showmanship element? The theatre . . . the dagger. I watched her examine the knife. I’ll swear it meant nothing to her. She was curious, fascinated even in a ghoulish way, but there was no flicker of recognition. Just an element of his past life she’d rather not think about. Why didn’t they simply have him pushed under a bus or off a bridge? And why wait all these years?’

Bonnefoye shrugged and poured out more wine. ‘Still – glad enough to have them as suspects two and three. I like to collect a good hand.’

Joe raised a questioning eyebrow. ‘Your first suspect?’

Jean-Philippe was suddenly grave. ‘Sir George, of course. I don’t like it any more than you do but the man’s up to his neck in whatever’s going on. You’d have to be blind not to see that.’

Joe produced the doctor’s copy of Le mort qui tue from his pocket and slapped it down on to the table between them. ‘Look at the title, Jean-Philippe. If we work with your suppositions, Sir George will die. An innocent man guillotined for a corpse we haven’t the wits to account for. Somerton will be the death of him, and with our cooperation. I can’t shake off the feeling that someone’s pulling our strings, playing the tune we’re dancing to. And that puts my back up! The pathologist, Dr Moulin, had some interesting observations to pass on. He’s formed theories which support Francine Raissac’s strange ideas.’