‘Eight,’ said Ben. ‘She was supposed to be on her way home.’

‘We’ve found her keys,’ said the CSM, ‘but still no phone. There’s a dive team coming to search the canal later.’

In the corner of the tent a technician dropped a pair of black ballet pumps into a bag. He put a red flag in the ground, then sealed the bag and signed across the seal. ‘Was that where they were found?’ she asked him.

He nodded. ‘Right there. Both of them.’

‘Kicked off? Pulled off?’

‘Taken off. They were like this.’ The CSM held out his hands, straight and neatly together. ‘Just placed there.’

‘Is that mud on them?’

‘Yes. But not from here. From the towpath somewhere.’

‘And this grass – the way it’s been flattened?’

‘The struggle.’

‘It’s not much,’ she said.

‘No. Seems to have been over quickly.’

The photographer had finished videoing. He stepped back to allow Zoë and Ben to approach the body. The tread plates divided into two directions at the foot of the tarpaulin and circled the body. Zoë and Ben went carefully, taking the side that led to Lorne’s face. They stood for a long time in silence, looking down at her. They’d both been working in CID for more than a decade and in that time they’d dealt with just a handful of murders. Nothing like this.

Zoë looked up at the CSM. She could feel her eyes wanting to water. ‘What’s made her face go like that?’

‘We’re not sure. We think it’s a tennis ball between her teeth.’

‘Christ,’ said Ben. ‘Christ.’

The CSM was right: a piece of duct tape had been placed across Lorne’s mouth. It was holding in place a spherical object that had been jammed inside as far as it would go, luminous green tufts visible at the top and bottom. It had forced her jaw open so wide she seemed to be snarling or screaming. Her nose was squashed into a bloodied clot, her eyes were screwed up tight. There was more blood in her hair. Two distinct lines of it ran from under the duct tape down to her jaw – almost in the places the jaw of a ventriloquist’s dummy would be hinged, except that they met her jaw almost under her ears. She must have been lying on her back when the bleeding had happened.