The mortician wrenched down the thick metal arm on the freezer door. The tops of three anonymous heads were revealed, stacked one above the other, each draped in a white sheet worn limp and fine through repeated washings. The mortician checked the tag pinned to the cloth covering the central head; it bore no name, only the previous day’s scribbled date. He slid the body out smoothly on its long-runnered tray and deposited it efficiently on to the waiting trolley. Strike noticed Carver’s jaw working as he stepped back, giving the mortician room to wheel the trolley clear of the freezer door. With a clunk and a slam, the remaining corpses vanished from view.

‘We won’t bother with a viewing room, seeing as we’re the only ones here,’ said the mortician briskly. ‘Light’s best in the middle,’ he added, positioning the trolley just beside the drain, and pulling back the sheet.

The body of Rochelle Onifade was revealed, bloated and distended, her face forever wiped of suspicion, replaced by a kind of empty wonder. Strike had known, from Wardle’s brief description on the telephone, whom he would see when the sheet was revealed, but the awful vulnerability of the dead struck him anew as he looked down on the body, far smaller than it had been when she had sat opposite him, consuming fries and concealing information.

Strike told them her name, spelling it so that both the mortician and Wardle could transcribe it accurately on to clipboard and notebook respectively; he also gave the only address he had ever known for her: St Elmo’s Hostel for the Homeless, in Hammersmith.

‘Who found her?’

‘River police hooked her out late last night,’ said Carver, speaking for the first time. His voice, with its south London accent, held a definite undertone of animosity. ‘Bodies usually take about three weeks to rise to the surface, eh?’ he added, directing the comment, more statement than question, at the mortician, who gave a tiny, cautious cough.

‘That’s the accepted average, but I wouldn’t be surprised if it turns out to be less in this case. There are certain indications…’

‘Yeah, well, we’ll get all that from the pathologist,’ said Carver, dismissively.

‘It can’t have been three weeks,’ said Strike, and the mortician gave him a tiny smile of solidarity.

‘Why not?’ demanded Carver.

‘Because I bought her a burger and chips two weeks ago yesterday.’

‘Ah,’ said the mortician, nodding at Strike across the body. ‘I was going to say that a lot of carbohydrates taken prior to death can affect the body’s buoyancy. There’s a degree of bloating…’

‘That’s when you gave her your card, is it?’ Wardle asked Strike.

‘Yeah. I’m surprised it was still legible.’

‘It was stuck in with her Oyster card, in a plastic cover inside her back jeans pocket. The plastic protected it.’

‘What was she wearing?’