Eight hundred yards away, at the arrivals section of zone G, Roy Grace, clutching his thick briefcase, and approaching from the opposite direction, stepped on to the parallel carriageway of the same moving walkway.

To Glenn’s relief the sea was calm, or at least about as calm as the English Channel was ever going to get. Even so, the powerboat was still pitching and rolling quite enough in the gentle swell. But so far he felt fine. The breakfast of two boiled eggs and dry toast that Bella had recommended was still safely inside his digestive system rather than becoming part of the boat’s colour scheme, and he hadn’t yet experienced any attack of the roundabouts that had done for him on his last voyage.

It was a cold but glorious day, with a steely-blue sky and bottle-green sea. A gull circled low overhead, on the scrounge and out of luck. Glenn breathed in the rich smells of salt and varnish, and the occasional waft of exhaust fumes, and watched a jellyfish the size of a tractor tyre drift past, deciding he was very happy not to be one of the team going into the water, despite all their protective clothing. He had never experienced any desire to jump out of an aeroplane, or to explore the bottom of the ocean. He’d figured out, a long time ago, that he was definitely a terra-firma kind of a guy.

The tiny red smudge in the distance grew closer as they powered steadily further out to sea, at a diagonal angle to Brighton’s long seafront, on the exact course he and Ray Packham had charted. As they approached closer still, the smudge sharpened into focus and he saw it was in fact a triangle of bobbing pink marker buoys, which the Specialist Search Unit team had placed there yesterday evening.

At the helm, PC Steve Hargrave – Gonzo – throttled back, and their speed dropped from eighteen knots to less than five. Glenn gripped the handrail in front of him, as the sudden loss of motion pushed him forwards. This boat, a thirty-five-foot Sunseeker, was a much more upmarket vessel than the Scoob-Eee. It had been chartered in a hurry from a local nightclub owner and was a proper gin palace, with leather chairs and padding all around, teak decking, an enclosed bridge and a luxurious saloon down below, not that any of those on board were using it other than as a storeroom for some of their kit.

Arf, in the SSU team uniform of black baseball cap, with the word police across the front, red windcheater, black trousers and black rubber boots, removed the microphone of the ship-to-shore radio from its cradle and spoke into it.

‘Hotel Uniform Oscar Oscar. This is Suspol Suspol on board MV Our Current Sea, calling Solent Coastguard.’

He heard a crackled response. ‘Solent Coastguard. Solent Coastguard. Channel sixty-seven. Over.’

‘This is Suspol,’ Arf repeated. ‘We have ten souls on board. Our position is thirteen nautical miles south-east of Shoreham Harbour.’ He gave the coordinates then announced, ‘We are over our dive area and about to commence.’

Again the crackly voice. ‘How many divers with you, Suspol, and how many in the water?’

‘Nine divers on board. Two going in.’

Gonzo pushed the twin throttle levers into neutral. Tania, standing beside him, made some adjustments on the controls to the right of the Humminbird scanner screen.

Glenn looked at the display on the left of the screen: 98ft. 09.52am. 3.2mph.

‘If you watch now, Glenn, we should just be coming over,’ Tania said, pointing at what looked like a straight, black tarmac road, divided by a white line, running vertically down the centre of the screen. On either side of it was a bluish tinted moonscape.

‘There!’ she called out excitedly.

In the left-hand lane of the black section he saw clearly a boat-shaped shadow, even darker, about half an inch long.

‘You think that’s her? The Scoob-Eee?’ he asked.

‘There’s one way to find out,’ Arf said. ‘Coming in with us?’

A flaccid, murky-looking object drifted past. Glenn wasn’t immediately sure if it was another jellyfish or a plastic bag.

‘Nah, think I’d better stay on deck and keep a lookout for pirates. But thanks all the same.’

Arf pointed at the sea. ‘If you change your mind, there’s plenty of room down there.’

‘Someone told me your father used to play tennis for Sussex, E-J,’ Guy Batchelor said. ‘I’m a bit of a player myself – well – used to be – but not that kind of standard. What’s his name?’

‘Nigel. He played for the under-sixteens – but he hasn’t played seriously for years. He could probably drink for Sussex now. Or, more likely, talk for Sussex.’ She grinned.

‘Gift of the gab?’

‘You could say.’

They were heading west, away from the village of Storrington, with the softly undulating South Downs to their left. She peered at the map on her knees.

‘Should be the next right.’

They turned into a narrow country lane, barely wider than the car and bounded by tall hedgerows. After a quarter of a mile, Emma-Jane directed him to turn left, into an even narrower lane. Police cars, Batchelor thought, were going to be the last vehicles on the planet without SatNav – and the ones that needed it the most. He was about to comment on that to E-J when he heard a muffled call-sign on his radio. Although he was driving, he lifted it to his ear, but it was a request for assistance in a different part of the county, not remotely near them.

‘Should be coming up on the left,’ Emma-Jane said.

He slowed the blue unmarked Mondeo down. Moments later they saw a pair of imposing wrought-iron gates between two pillars topped with stone balls. Written in gold letters on a black plate was the name, THAKEHAM PARK.

They pulled up in front of the gates, under the cyclops gaze of a security camera mounted high up. On the opposite pillar was a yellow sign, with a grinning face, beneath which was written the legend SMILE, YOU ARE ON CCTV.

The young DC climbed out and pressed the button on the speakerphone panel beneath. Moments later, she heard a crackly, broken-English, female voice.

‘Hello?’

‘Detective Sergeant Batchelor and Detective Constable Bout-wood,’ she announced. ‘We have an appointment with Sir Roger Sirius.’

There was a sharp crackle from the speakerphone, then the gates began to open. She climbed back into the car and they drove through, along a tarmac drive, lined by mature trees on either side, which wound steadily for about half a mile up an incline. Then a huge Jacobean mansion came into view, with a circular driveway in front, in the grassed-in centre of which was a lily pond.

Several cars were parked in front of the house including, Guy recognized, a black Aston Martin Vanquish. To their right, on a large concrete circle in the middle of a manicured lawn, sat a dark blue helicopter.

‘Seems like there’s money in medicine!’ he commented.

‘If you are in the right area of it,’ she retorted.

‘Or maybe the wrong area,’ he corrected her.

Emma-Jane did not even bother trying to count the number of windows. This place must have twenty or thirty bedrooms – maybe more. It was on the scale of a stately home.

‘I think we chose the wrong career,’ she said.

He drove slowly around the pond and pulled up almost directly in front of the grand front door. ‘Depends what you want out of life, doesn’t it? And the moral code by which you choose to live.’

‘Yes, I suppose so.’

‘Have you ever met Jack Skerritt?’

‘A few times,’ she said. ‘But only briefly.’

Jack Skerritt was the Chief Superintendent of HQ CID – the most senior detective in Sussex. And the most respected.