Ben put his hands in his pockets and squinted up at the sky. ‘So?’ he said quietly. ‘What do you think’s under that tarp?’

‘Christ knows.’

‘Boss?’ DC Goods, one of the team, was coming along the path towards them, waving to attract their attention. ‘I’ve got a woman wants to speak to you.’

‘A woman?’

‘One of the live-aboards. Some of the owners got a good view of the crime scene before it was cordoned. They got the lie of the land. This one saw the body – just a glimpse. She’s got something she wants to tell you.’

‘Great.’ Zoë set off down the path at a pace, Ben a few steps behind her. Her head was buzzing. It would be really nice – really nice – to tuck a solved murder into her portfolio. Be able to stand up in front of the force and Lorne Wood’s family and say she’d found the killer. The person who’d shoved a tennis ball into their daughter’s mouth. And done God only knew what else to her.

The barge wasn’t far from the park – at least a quarter of a mile from the crime scene. It was brightly painted, with flowers daubed all over the cabin, the name Elfwood carved across the stern. On the roof, next to the little chimney, were piled provisions – coal, wood, water bottles, a bicycle. Ben rapped twice on the roof, then jumped on to the aft deck and bent to look down into the cabin. ‘Hello?’

‘I’m here,’ said a voice. ‘Come in.’

He and Zoë went down the steps, bending their necks to avoid the low ceiling. It was like going into Aladdin’s cave – every surface, the ceiling, the walls, the cupboards, had been adorned with wooden sculptures of tree nymphs. The windows were hung with glittering cheesecloth in shades of purple and pink, and everything smelt of cats and patchouli oil. Not much sunlight filtered through, just enough for them to make out a woman of about fifty, with very long curly hennaed hair, perched on one of the bulkhead seats, a roll-up cigarette in her hand.