Roy Grace shivered. Although he had on thick jeans, a heavy-knit pullover and lined boots under his paper suit, the damp inside the storm drain and the rain outside were getting into his bones.

The SOCOs and search officers, who had the unpleasant task of checking every inch of the drain, mostly on their hands and knees, had so far found a few rodent skeletons, but nothing of interest. Either the dead woman’s clothing had been removed before she was deposited here, or it had been washed away, rotted or even taken for animals’ nests. Working painstakingly slowly with trowels, Joan Major and Frazer Theobald were scraping away the silt around the pelvis, bagging and tagging each layer of dirt separately in neat cellophane bags. They would be another two or three hours at this rate, Grace estimated.

And all the time he was drawn back to the grinning skull. The sensation that Sandy’s spirit was here with him. Could it really be you? he wondered, staring hard. Every medium he had been to in the past nine years had told him that his wife was not in the spirit world. Which meant she was still alive – if he believed them. But none had been able to say where she was.

A chill fluttered through him. This time it was not the cold, but something else. He had determined a while ago to find closure and move forward with his life. But each time he tried, something happened that sowed doubt in him, and it was happening again now.

The crackle of his radio phone startled him out of his reverie. He held it to his ear with a curt, ‘Roy Grace?’

‘Morning, Roy. Your career going down the drain, is it?’ Then he heard Norman Potting’s throaty chuckle.

‘Very funny, Norman. Where are you?’

‘With the scene guard. Want me to get togged up and come down?’

‘No, I’ll come to you – meet me in the SOCO van.’

Grace welcomed the excuse to get away for a bit. He wasn’t strictly needed here and could easily have gone back to his office, but he liked his team to see him leading from the front. If they were having to spend their Saturday inside a dank, horrible drain, at least they could see his day wasn’t any better.

It was a relief to shut the door on the elements and sit down on the soft upholstery at the work table in the van. Even if it meant being confined in a small area with Norman Potting – never an experience he relished. He could smell the stale pipe smoke coming off the man’s clothes, mixed with a strong reminder of last night’s garlic.

Detective Sergeant Norman Potting had a narrow, rather rubbery face criss-crossed with broken veins, protruding lips and a thinning comb-over, part of which, at this moment was sticking bolt upright, having been blasted by the elements. He was fifty-three, although those who particularly disliked him spread rumours that he had knocked several years off his age so he could stay in the force longer, because he was terrified of retirement.

Grace had never seen Potting without a tie and this morning was no exception. The man was wearing a long, wet anorak with duffel tags over a tweed jacket, Viyella shirt and a fraying green knitted tie, grey flannel trousers and stout brogues. With a wheezing sound, he eased himself behind the table, on to the bench seat opposite Grace, then plonked down a large, dripping-wet cellophane folder, looking triumphant.

‘Why do people always pick such bleedin’ awful places to get murdered or dumped in?’ he said, leaning forward and exhaling directly into Roy’s face.

Trying not to wince as a blast furnace of hot and rancid smells enveloped him, Roy decided that this was probably what being breathed on by a dragon would be like. ‘Maybe you should draw up some guidelines,’ he said testily. ‘A fifty-point code of practice for murder victims to abide by.’

Subtlety had never been Norman Potting’s strong point and it took him a moment now to realize that the Detective Superintendent was being sarcastic. Then he broke into a grin, showing a mouthful of stained, crooked teeth, like tombstones on subsiding ground.

He raised a finger. ‘I’m rather slow this morning, Roy. Had a bit of a night last night. Li was like a bloody tiger!’

Potting had recently ‘acquired’ a Thai bride and constantly regaled anyone in earshot with details of his new-found prowess in bed with her.

Heading off the subject rapidly, Grace pointed at the cellophane folder. ‘You got the plans?’

‘Four times last night, Roy! And she’s a dirty cow – do anything! Phoawwww! She makes me a very happy man!’

‘Good.’

For a brief moment, Grace actually felt pleased for him. Potting had never had a lot of luck in his love life. He was a veteran of three marriages, with several children he had once admitted, ruefully, that he rarely saw. The youngest was a girl with Down’s syndrome whom he had tried and failed to get custody of. He wasn’t a bad or a stupid person, Roy knew – he was a very competent detective – but he lacked the social skills essential to rising any higher in the force, should he want to. Still, Norman Potting was a solid and dependable workhorse, with sometimes surprising initiative, and those aspects of him were far more important in any major inquiry, in his view.

‘You should consider it yourself, Roy.’

‘Consider what?’

‘Getting a Thai bride. Hundreds of them gagging for an English husband. I’ll give you the website – they are bloody wonderful, I tell you. They cook, clean, do all your ironing, give you the best sex of your life – lovely little bodies-’

‘The plans?’ Grace said, ignoring the last remark.

‘Ah, yes.’

Potting shook several large photocopies of street maps, grids and section drawings out of the folder and spread them over the table. Some of them dated back to the nineteenth century.

Wind rocked the van. Outside, somewhere in the distance, an emergency service siren sounded and then faded away. The rain drummed steadily on the roof.

Plans had never been something that Roy found easy to follow, so he let Potting talk him through the complexities of Brighton and Hove’s drainage system, using the paperwork and briefing which had been given to him by a corporation engineer earlier this morning. The DS ran a grimy-nailed finger across, down, then up each of the drawings in turn, showing how the water ran, always downhill, eventually out into the sea.

Roy tried hard to keep up with him, but half an hour on he was little wiser than he had been before he started. It seemed to him that it all added up to the fact that the weight of the dead woman’s body had jammed her in the silt, while anything else would have been washed down the drain, into the trap and out to sea.

Potting concurred with him.

Grace’s phone rang again. Excusing himself, he answered it, and his heart immediately sank as he heard the dentist’s-drill voice of freshly appointed Detective Superintendent Cassian Pewe. The slimeball from the Met his boss had brought in to eat his lunch.

‘Hello, Roy,’ Pewe said. Even distanced by a phone connection, Grace had the impression that Pewe’s smug, pretty-boy face was pressed claustrophobically up against his own. ‘Alison Vosper suggested I give you a call – to see if you needed a hand.’

‘Well, that’s very kind of you, Cassian,’ he replied. ‘But no, actually, the body’s intact – I’ve got both of her hands here.’

There was a silence. Pewe made a sound like a man who has started to urinate against an electric fence. A kind of stilted laughter. ‘Oh, very funny, Roy,’ he patronized. Then, after an awkward silence, he added, ‘You’ve got all the SOCOs and search officers you need?’

Grace felt a band tighten inside him. Somehow he restrained himself from telling the man to go and find something else to do with his Saturday. ‘Thank you,’ he said instead.