“There,” he said, pointing across the valley. The reservoir was a kilometre wide, the bridge on which they stood, about halfway across it. Directly opposite them at the furthest point, Lauren Tranter could be seen, ankle deep in the water, looking down. To Harper she looked almost childlike in that moment, her shoulders hunched against the noise from the helicopter hovering above them. Harper shouted above the din, pointing up, “Can’t you get them to pull back? It’s frightening her.”

Thrupp nodded and spoke into his radio briefly. The craft flew over their heads, back towards the city, not leaving entirely but holding position in a big circle as if trying to land. They wouldn’t find anywhere near—everything in the valley was either reservoir or densely wooded slopes.

After the helicopter had retreated, Lauren stepped back from the edge of the water and seemed to collapse to a sitting position.

“She’s not going in. Thank goodness,” said Thrupp, and breathed out heavily. One of the uniformed officers clapped Harper on the shoulder but she shook the hand away, concentrating on Lauren, who was staring out at the water, still clutching the two bundles. Thrupp handed her a pair of binoculars. Through them she could see the waving arms of the infants, and Lauren’s unreadable face. There was no way of telling what she might do next, and until an officer reached Lauren on the shore, the babies were still in danger. Harper calculated the distance across. She could swim that in six minutes, if she had to. She’d done it in training, but not from this side of the reservoir, where the water had dropped so low that yellow Danger signs, usually flush with the surface, stuck out on the ends of their long poles.

Thrupp raised his radio to listen to a transmission. “The ground team have got eyes on her,” he said, “but they can’t see a way through. It’s dense brambles all the way up that part of the valley.”

“Where’s Patrick?” said Harper, trying not to spit the name out.

“He went round the other way. He’s already over there with the search team.”

“I’ll go, too.” She started to move towards the car, but Thrupp called her back.

“Don’t bother, it’s a ten-minute drive, at the very least. Listen, Jo—”

But Harper cut him off by thrusting the binoculars back at him. She kicked off her shoes and climbed to the top of the railing.

“Hey, what are you doing?” he said, before he swung round and saw what she’d already seen—Lauren Tranter was no longer sitting on the far shore. She had stood up and was walking towards the water.