As one, they all looked down at the woman’s body. Mrs Hawksmith was past middle age but not yet old. Each of her ankles was bound by a cable tie to a tap pipe, below the handle, at the end of the bath, leaving her legs splayed open, slightly bent, and flopped against the sides. Her wrists were bound with handcuffs over her stomach. A deep wound – Ava estimated three inches long – ran across the inner bend of her left elbow with another, shorter one, on the same wrist. Her head lolled against the side nearest them, eyes open, mouth agape, as if she were appealing for help.

The corpse was bloated, limbs swollen and hard, a dark red colour with brown patches. The putrefaction gases were appalling, even though the doors had been open for some time. She was a large woman but not obese. Her tattoos were visible but not clear through the discolouration of her skin and there were no other obvious wounds. The goriest of tidemarks was a muddy-crimson line around the rim of the tub and the plug remained in place.

‘The bath was full when she bled out,’ Ava said. ‘The water must have leaked out slowly in the days that followed. Has anyone found the key to the handcuffs?’ she asked Tripp, leaning over to take a closer look at the cuffs.

They weren’t police or military issue, nor were they the joke shop sort with the button that could be pressed to spring them open. A key had to be fitted into a central slot to release the wearer, which would have been possible if the key was within grabbing distance.

‘No key as yet,’ Tripp said. ‘You can get those sort of cuffs online or in sex shops. They’re bondage-type regalia. Maybe she was tomming.’

‘Okay, get asking the neighbours if there were men – or women, for that matter – coming to the flat at odd hours, or if Mrs Hawksmith was coming and going at unusual times. Does she have any previous convictions?’

‘Still checking. We don’t have a confirmed date of birth yet. She doesn’t have a passport or driving licence here that we’ve found.’

‘Do we know what the cut was made with?’ Ava looked around the tiny bathroom.

‘We haven’t found a blade or a weapon,’ Tripp said.

‘Really?’ Ava asked. ‘Is there blood anywhere else in the property?’ She tried to peer through the plastic sheeting beneath her feet. ‘Blood on the bathroom floor, even?’

‘None,’ Ailsa said, appearing behind Tripp. ‘Excuse me, young man.’

Tripp moved out of her way to let her stand over the body with a thermometer.