'What do you mean?'

'Neither of us believes she died accidentally, do we? Or by her own hand. She must have strayed too close to the truth. How close, I assume you don't know, otherwise you wouldn't be here. The desire to avenge her is doubtless considerable, but -'

Umber stood up suddenly, pushing his chair back against the vacant table behind him with a thump. It stopped Nevinson in mid-sentence. He goggled up at Umber in surprise.

'What's wrong?'

'Nothing's wrong. I'm leaving. That's all.' Umber plucked a fiver out of his wallet and tossed it onto the table. 'Not sure that'll stretch to the cake, but I'll have to leave you to settle up, I'm afraid.'

'But… we haven't finished.'

'Oh yes, we have.' Umber smiled stiffly. 'I've heard enough.'

Umber needed a walk to calm himself before reporting back to Sharp. In the course of it, he began to suspect that Sharp would criticize him for failing to confine Nevinson to practical issues. But there it was. The man was impossible. He was also, Umber felt sure, irrelevant.

As it turned out, Umber had more time to prepare his excuses than he thought. When he reached the Ivy House, he was handed a note from Sharp. Have gone to Devizes. Back later. As messages went, it was less than illuminating.

Wiltshire Constabulary Headquarters was in Devizes. That fact, once quarried from Umber's memory, lodged stubbornly at the fore of his thoughts as he awaited Sharp's return. Eventually, he quit the hotel in search of dinner. On his way back from the restaurant he wandered into the Green Dragon, a quiet, smoky pub, where he sat by the fire with a pint and did his level best not to imagine what conspiracy theories Nevinson might concoct if he knew of Sharp's unannounced journey. This exercise in mental discipline was itself partly designed to prevent his dwelling on Nevinson's absurd notion that Sally had been murdered. Down that road, Umber feared, lay his own brand of madness.

At some point he remembered, to his irritation, a question he had meant to put to Nevinson. What had he wanted to show Jeremy Hall at the Adam and Eve stones that day in July 1981? It was a magnifying glass Umber had seen flash in the sunlight. He knew that because he had noticed it clutched in Nevinson's hand as they stood together at the roadside. But what had he been using the glass for? What had he been looking at? Marks on one of the stones that he believed were Martian runes, in all likelihood, but-

'There you are, Umber.' George Sharp loomed suddenly into view. 'This is the third pub I've tried. Want a half in there?'

Taken aback as much by Sharp's unwonted jollity as his unheralded arrival, Umber mumbled his thanks and struggled to order his thoughts while Sharp bought the drinks. The pub was far from busy, however. Sharp was back within a couple of minutes.

'I've missed the Wadworth's up in Derbyshire,' he announced, taking a deep swallow of 6X as he sat down. 'But it must be nectar for you after that gnat's piss you've had to make do with in Prague.'

'Was it the beer that took you to Devizes, George? The brewery's there, isn't it?'

'Very funny. I actually went to meet an old pal of mine. Johnny Rawlings. Just about the last serving police officer I still know. He's winding down to retirement with a desk job at Headquarters. He's the only one there I can be sure will do his best to help rather than hinder and will keep quiet into the bargain. I wanted to bend his ear about the Radd case. But we'll get back to what he told me later. What did you glean from Percy Nevinson?'

'What I gleaned was that his choice of fruit cake to sop up his tea was all too appropriate. He's convinced Tamsin was taken by government agents to frighten him into silence about his theory explaining the Martian origins of Avebury.'

'Still stuck in that groove, is he?'

'Never likely to emerge from it, as far as I can see.'

'So, like I said, a nutter.'

'Fully paid-up.'

'Unless

'Are you going to suggest it's all camouflage, George? A plan to have us think him a nutter when he's really… what, exactly? A co-conspirator of Tamsin's abductors?'

'You obviously don't think that's what he is.'

'No. I don't.'

'Then we'll agree to put him on the back burner for the time being. Not off the stove altogether, mind. I mean to keep my eye on him. Now, as for Johnny Rawlings -'

'Why didn't you tell me you were going to see him?'

'Oh, it was a spur-of-the-moment decision. You were busy with the Man from Mars. I thought I ought to keep busy myself. Besides, I've been planning to drop in on Johnny. It was just a question of timing. I contacted him before I went to Prague, as a matter of fact. Asked a favour of him. Reckoned it wasn't too soon to check if he'd been able to swing it for me. When I phoned, he was up for an after-work pint, so I drove straight over.'

'What was the favour?'

'Two favours, really. One, the low-down on Radd's confession. Was it solicited? Was there a deal?'

'You said there couldn't have been.'

'Well, it seems I was right. Johnny's had a squint through the files. Radd confessed out of the blue. No-one here or at Thames Valley had even thought of pinning Avebury on him until he did it himself. And no-one can understand why he should have done – unless he was telling the truth.'

'Which we know he wasn't.'

'That brings me to favour number two. I asked Johnny if he could fix it for me to meet the man himself: Brian Radd. The best way to be sure if he's lying is to look him in the eye when he tells me his tale. Well, Johnny's come through with a visiting order. I'm in.'

'When will you go to see him?'

'When it suits. Radd's in Whitemoor, up in Cambridgeshire. That must be a three-hundred-mile round trip. It'll have to wait until we've spoken to Jane Questred.'

'She hasn't called.'

'She will.' Sharp grinned at Umber. 'I'm banking on it.'

Jane Questred never made the call Sharp had so confidently anticipated. But she was in touch, via her husband, who phoned Umber during a late breakfast the following morning. Hearing Edmund Questred's voice, Umber at once expected to be told that she had refused to see them. But not so.

Two hours later, Sharp nosed the van through the open gate next to Swanpool Cottage and pulled up in front of the garage. The cottage was timber-framed and thatched, every bit as chocolate-box as Abigail Nevinson had claimed. A swag of wisteria obscured the gable end. The brickwork, where visible, was intricately patterned and immaculately pointed. Grand it might not have been, but beautiful it certainly was.

The front door opened as they approached and Jane Questred stepped out to greet them. A slim, elegant woman in her mid-fifties with grey-blonde hair and delicate features, she was dressed plainly in a dark top and black trousers. Her expression was studiously neutral. She looked less wary than cautious, self-controlled and better equipped to cope with an intrusion from her traumatic past than her husband's protectiveness had suggested.

'Mr Sharp. Mr Umber.' They shook hands. 'You found your way, then.'

'Thank you for agreeing to see us, Mrs Questred,' said Sharp.

'Did I have a choice in the matter?'

The question went unanswered as she led them into a surprisingly large sitting room that looked as photogenic as the exterior, pastel-toned sofas and downland watercolours blending tastefully with exposed beams and a big, rough-hewn fireplace. There was an aroma of freshly ground coffee, explained by a cafetiere standing with some cups and saucers on a table in front of the fire.