Every narrow street he looked down called to mind a scene already captured in paint or waiting to be captured. He turned a corner into the rue St-Vincent and found himself following a few paces behind a figure from the last century. In baggy black suit and wide-brimmed gypsy hat, guitar slung across his back, a chansonnier strolled on his way to perform perhaps at the Lapin Agile. Conscious that he was wasting time, Joe tracked him until he disappeared into the dilapidated little cottage, his entrance marked by raucous cries of welcome and a burst of song. For a moment Joe paused, tempted to go into the smoky depths. He remembered that in an earlier age it had been known as the Cabaret des Assassins.

Who would he see in there if he slid inside and took a table? He narrowed his eyes and pictured the scene. Letting his fancy off the leash, he saw: Picasso . . . Apollinaire . . . Utrillo . . . Jean Cocteau . . . and he grinned. He probably wouldn’t understand a word of the conversation! Avant-garde, fast-living, arty . . . But he knew who would understand and almost turned to share his thoughts with young Dorcas. He felt a stab of regret that his adopted niece who’d trailed through France with him last summer was not by his side. She’d have felt at home here. She’d have greeted the gypsy guitarist and talked to him in his own language. Her raffish father, Orlando, must have spent hours drinking and yarning with his fellow painters in this picturesque hovel, judging by the quantities of canvases it had inspired. And his daughter was probably on first-name terms with half the clientele!

He looked at his watch. Better left for another day. Yes, he’d come back some other time. With Dorcas. Why not? He reminded himself to find a suitable postcard to send to her in Surrey. But a different girl was higher on his agenda today.

He had work to do. A self-imposed task but tricky and not one to be attempted light-heartedly. Not heavy-handedly either though. He looked around and caught sight of a flower seller’s stall on a corner of the square. Five minutes later, armed with half a dozen of the best red roses the seller could provide, done up in a silver ribbon, he locked on to his target.

Everyone who could be outside on that May afternoon was out on the pavement. The concierges of the lodging houses had settled in chattering groups, shelling peas, their chairs obstructing the pavements. From open doors behind them drifted the fragrant smell of dishes cooking slowly in some back room. Mothers fed babies or crooned them to sleep.

Around a corner to the north of the square he came upon the faded blue sign he was looking for: rue St Rustique. The oldest street in the village and quite probably the narrowest. The three- and four-storey houses had known better days. Shabby grey façades retained interesting architectural features: elegantly moulded architraves graced doorways, Second Empire wrought-iron grilles added dignity to windows whose shutters stood wide open on to the street. Bourgeois net curtains gave seclusion and an air of mystery to the interiors.

Joe located number 78. The patch of pavement in front of the house and the cobbled road as far as the central gutter were freshly cleaned. Abroom was propped against the wall to the right of the open door, two large pots of daisies stood to attention and an eye-watering waft of eau de javel leapt from the interior and repelled him. Joe read the sign painted in art nouveau letters above the door’s architrave: Concierge.

He froze. There she was, filling the doorway, barring his entrance. Redoubtable. Cerberus? The Cyclops? He reckoned he had about as much chance of getting past her and into the building as he would have had facing up to one of those monstrous guardians. She stood, four-square, bulldog face peering at him over gold half-moon spectacles. She was holding a pile of letters to the light and shuffling through them. Sorting out the residents’ afternoon post, he guessed, and she was not counting on being disturbed. She was dressed like a badly done-up parcel; her clothes were all in shades of brown, shapeless and hanging in layers to her mid-calf. Here the tale of sartorial disaster was taken up by a pair of drooping socks and bulging slippers.

Joe did not often find himself at a loss for words and was angry with himself for hesitating to address her. He regretted now the bunch of roses in his hand. What a twerp he must look.

‘Yes? Who are you?’ Her voice would not have disgraced a sergeant major.

The challenge provoked a military response. He stood at ease in front of her with what he hoped was an air of languid confidence and managed a tight smile. ‘An English gentleman to see Mademoiselle Raissac. I understand she lives here.’ He began to reach into his pocket for his warrant card.

She stopped him with a gesture. ‘She’s not seeing callers today. She’s not well. Come back tomorrow.’ The concierge turned and, as an afterthought, seized her broom as though she thought he might run off with it. She made to go back inside.

‘Police! Wait!’

That claimed her attention. She came towards him. ‘Shh! Keep your voice down! This is a respectable street,’ she hissed at him. ‘Police? Again? She’s given a statement. Can’t you leave her alone?’

‘I will see her here, discreetly, in her own room, for half an hour or I will haul her off to the Quai des Orfèvres for a rather lengthier interview. I’m quite certain neither you nor the young lady would relish the appearance of a panier à salade outside your front door, madame.’ Joe was not at all certain that one of these sinister motorized cells would be deployed at his request for the conveyance of one suspect but the old dragon appeared impressed by the threat.

‘You’d better come in then . . . sir. And you can show me your proof of identity.’ Her voice would never be capable of expressing deference but at least it was now verging on the polite. ‘You can wait in my parlour while I go up and see if she’s prepared to see you. Through here.’

She took him to her two-roomed loge on the ground floor off the hallway and offered him a hard-backed chair. The small room which served as both kitchen and living room was sparsely furnished but neat and well polished. A few ornaments twinkled on the mantelpiece above an open fire on which a blackened pot had been left to simmer. Monsieur’s supper no doubt.

She wiped her hands on her pinny and reached for the warrant card he held out to her. Every aspect of it came under her searching eye and finally: ‘Well, it’s good that the flics are taking a serious interest in this tragedy. Bit unusual, isn’t it? Not something we’re used to round here – courtesy visits from the Law with roses in its hand. Have a glass of water while you’re waiting, young man. You look overheated,’ she said, surprising him, and poured a glass from the tap. ‘Don’t pull that face! No need to be fussy! Paris water is good water.’

Joe drank gratefully, puzzled but relieved by her change of attitude. On a whim, he reached into his pocket and took out the bag of coffee beans. ‘For you, madame. I hope you can drink coffee?’

The tight lips twitched slightly and she took the bag from him, squinting at the label. ‘From La Bordelaise! I can certainly drink that! Thank you very much.’ She set it down on a dresser beside the polished copper funnel of a coffee-grinder and went to summon her lodger. In the doorway, she turned and spoke to him over her shoulder in her clipped, machine-gun phrases. ‘Francine is a good girl. Never been in trouble with the law. She works every hour God sends. As good as a daughter to me. And she’s still reeling from the shock. You’re to treat her with respect.’

Joe’s saluting arm twitched in automatic response to the tone.

As her slippered feet thudded up the staircase, he eyed the coffee. A sop to Cerberus? It still seemed to work.