After Sumburgh Airport, there was nothing but sea and a sky wider than any Rebus had seen before, thin clouds strung across it. The twin-engined Puma flew low and loud. The interior was cramped, and so were the survival suits they’d been made to put on. Rebus’s was a bright orange one-piece with a hood, and he’d been ordered to keep it zipped up to his chin. The pilot wanted him to keep his hood up, too, but Rebus found that sitting down with the hood tight across his head, the legs of the suit threatened to dissect his scrotum. He’d been in choppers before – back in army days – but for short hops only. Designs might have changed over the years, but the Puma didn’t sound any quieter than the old buckets the army had used. Everyone, however, wore ear-protectors, through which the pilot could talk to them. Two other men, contract engineers, flew with them. From flying height, the North Sea looked tranquil, a gentle rise and fall showing the currents. The water looked black, but that was just cloud cover. The brochure had gone into great detail concerning anti-pollution measures. Rebus tried to read his book, but couldn’t. It juddered on his knees, blurring the words, and he couldn’t keep his mind on the story anyway. Lumsden was looking out of the window, squinting into the light. Rebus knew Lumsden was keeping an eye on him, and he was doing so because Rebus had touched a nerve last night. Lumsden tapped his shoulder, pointed through the window.

There were three rigs below them, off to the east. A tanker was moving away from one of them. Tall flares sent bright yellow flames licking into the sky. The pilot told them they would pass to the west of the Ninian and Brent fields before reaching Bannock. Later, he came back on the radio.

‘This is Bannock coming up now.’

Rebus looked past Lumsden’s shoulder, saw the single platform coming into view. The tallest structure on it was the flare, but there were no flames. That was because Bannock was coming to the end of its useful life. Very little gas and oil were left to exploit. Next to the flare was a tower, like a cross between an industrial chimney and a space rocket. It was painted with red and white stripes, like the flare. It was probably the drilling tower. Rebus made out the words T-Bird Oil on the jacket below it, along with the block number – 211/7. Three large cranes stood against one edge of the platform, while a whole corner was given over to a helipad, painted green with a yellow circle surrounding the letter H. Rebus thought: one gust could have us over the side. There was a two hundred foot drop to the waiting sea. Orange lifeboats clung to the underside of the jacket, and in another corner sat layers of white portacabins, like bulk containers. A ship sat alongside the platform – the safety and support vessel.