Strike was, in fact, proving to himself that the logical route from the Bestiguis’ bedroom to their bathroom was through the hall, bypassing the sitting room altogether. Furthermore, it was his belief that the only place in the flat from which Tansy could conceivably have witnessed the fatal fall of Lula Landry – and realised what she was seeing – was from the sitting room. In spite of Eric Wardle’s assertion to the contrary, nobody standing in the bathroom could have had more than a partial view of the window past which Landry had fallen: insufficient, at night, to be sure that whatever had fallen was a human, let alone to identify which human it had been.

Strike returned to the bedroom. Now that he was in solitary possession of the marital home, Bestigui was sleeping on the side nearest the door and the hall, judging by the clutter of pills, glasses and books piled on that bedside table. Strike wondered whether this had been the case while he cohabited with his wife.

A large walk-in wardrobe with mirrored doors led off the bedroom. It was full of Italian suits and shirts from Turnbull & Asser. Two shallow subdivided drawers were devoted entirely to cufflinks in gold and platinum. There was a safe behind a false panel at the back of the shoe racks.

‘I think that’s everything in here,’ Strike told Wilson, rejoining the other two in the sitting room.

Wilson set the alarm when they left the flat.

‘You know all the codes for the different flats?’

‘Yeah,’ said Wilson. ‘Gotta, in case they go off.’

They climbed the stairs to the second floor. The staircase turned so tightly around the lift shaft that it was a succession of blind corners. The door to Flat 2 was identical to that of Flat 1, except that it was standing ajar. They could hear the growl of Lechsinka’s vacuum cleaner from inside.

‘We got Mister an’ Missus Kolchak in here now,’ said Wilson. ‘Ukrainian.’

The hallway was identical in shape to that of number 1, with many of the same features, including the alarm keypad on the wall at right angles to the front door; but it was tiled instead of carpeted. A large gilt mirror faced the entrance instead of a painting, and two fragile, spindly wooden tables on either side of it bore ornate Tiffany lamps.

‘Were Bestigui’s roses on something like that?’ asked Strike.

‘On one that’s jus’ like ’em, yeah,’ said Wilson. ‘It’s back in the lounge now.’

‘And you put it here, in the middle of the hall, with the roses on it?’

‘Yeah, Bestigui wanted Macc to see ’em soon as he walked in, but there was plenty of room to walk around ’em, you can see that. No need to knock ’em over. But he was young, the copper,’ said Wilson tolerantly.

‘Where are the panic buttons you told me about?’ Strike asked.