“Right then,” said DI Layborn, closing the cupboard and walking over to a computer monitor. “Time to see the little lady in action.”

He inserted a video disk in the nearest machine, beckoning Strike, Robin and Wardle closer.

The crowded forecourt of Paddington station was revealed, jerky black and white figures moving everywhere. The time and date showed in the upper left corner.

“There she is,” said Layborn, hitting “pause” and pointing a stubby figure at a woman. “See her?”

Even though blurred, the figure was recognizable as Kinvara. A bearded man had been caught in the frame, staring, probably because her coat hung open, revealing the clinging black dress she had worn to the Paralympian reception. Layborn pressed “play” again.

“Watch her, watch her—gives to the homeless—”

Kinvara had donated to a swaddled man holding a cup in a doorway.

“—watch her,” Layborn said unnecessarily, “straight up to the railway worker—pointless question—shows him her ticket… watch her, now… off to the platform, stops and asks another bloke a question, making sure she’s remembered every bloody step of the way, even if she’s not caught on camera… aaaand… onto the train.”

The picture twitched and changed. A train was pulling into the station at Swindon. Kinvara got off, talking to another woman.

“See?” said Layborn. “Still making damn sure people remember her, just in case. And—”

The picture changed again, to that of the car park at Swindon station.

“—there she is,” said Layborn, “car’s parked right near the camera, conveniently. In she gets and off she goes. Gets home, insists the stable girl stays overnight, sleeps in the next room, goes outside next morning to ride within sight of the girl… cast-iron alibi.

“Course, like you, we’d already come to the conclusion that if it was murder, it must have been a two-person job.”

“Because of the orange juice?” asked Robin.

“Mostly,” said Layborn. “If Chiswell” (he said the name as it was spelled) “had taken amitriptyline unknowingly, the most likely explanation was that he’d poured himself doctored juice out of a carton in the fridge, but the carton in the bin was undoctored and only had his prints on.”

“Easy to get his prints on small objects once he was dead, though,” said Strike. “Just press his hand onto them.”

“Exactly,” said Layborn, striding over the wall of photographs and pointing at a close-up of the pestle and mortar. “So we went back to this. The way Chiswell’s prints are positioned and the way the powdered residue was sitting there pointed to it being faked, which meant the doctored juice could have been fixed up hours in advance, by somebody who had a key, who knew which anti-depressants the wife was on, that Chiswell’s sense of taste and smell were impaired and that he always drank juice in the mornings. Then all they’d need to do is have the accomplice plant an undoctored juice carton in the bin with his dead handprint on, and take away the one with the amitriptyline residue in it.

“Well, who’s better positioned to know and do all of that, than the missus?” asked Layborn rhetorically. “But here she was, with her cast-iron alibi for time of death, seventy-odd miles away when he was gulping down anti-depressants. Not to mention she’s left that letter, trying to give us a nice clean story: husband already facing bankruptcy and blackmail realizes his wife’s leaving him, which tips him over the edge, so he tops himself.

“But,” said Layborn, pointing at the enlarged picture of the dead Chiswell’s face, stripped of its plastic bag, revealing a deep red scrape on the cheek, “we didn’t like the look of that. We thought from the first that was suspicious. Amitriptyline in overdose can cause agitation as well as sleepiness. That mark looked as though somebody else forced the bag over his head.

“Then there was the open door. The last person in or out didn’t know there was a trick to closing it properly, so it didn’t look like Chiswell was the last person to touch it. Plus, the packaging on the pills being absent—that smelled wrong from the start. Why would Jasper Chiswell get rid of it?” asked Layborn. “Just a few little careless mistakes.”

“It nearly came off,” said Strike. “If only Chiswell had been put to sleep by the amitriptyline as intended, and if they’d thought the thing through right to the finest details—close the door properly, leave the pill packaging in situ—”

“But they didn’t,” said Layborn, “and she’s not smart enough on her own to talk herself out of this.”

“‘I can’t believe this is happening,’” Strike quoted. “She’s consistent. On Saturday night she told us ‘I didn’t think this would happen,’ ‘it didn’t seem real—’”

“Try that in court,” said Wardle quietly.

“Yeah, what were you expecting, love, when you crushed up a load of pills and put them in his orange juice?” said Layborn. “Guilty is as guilty does.”

“Amazing, the lies people can tell themselves when they’re drifting along in the wake of a stronger personality,” said Strike. “I’ll bet you a tenner that when McMurran finally breaks her, Kinvara’ll say they started off hoping Chiswell would kill himself, then trying to pressure him into doing it, and finally reached a point when there didn’t seem much difference between trying to push him into suicide, and putting the pills in his orange juice herself. I notice she’s still trying to push the gallows business as the reason he’d top himself.”

“That was very good work of yours, connecting the dots on the gallows,” admitted Layborn. “We were a bit behind you on that, but it explained a hell of a lot. This is highly confidential,” he added, taking a brown envelope off a nearby desk and tipping out a large photograph, “but we had this from the Foreign Office this morning. As you can see—”

Robin, who had gone to look, half-wished she hadn’t. What was there to be gained, really, from seeing the corpse of what seemed to be a teenage boy, whose eyes had been picked out by carrion birds, and hanging from a gallows in a rubble-strewn street? The boy’s dangling feet were bare. Somebody, Robin guessed, had stolen his trainers.

“The lorry containing the second pair of gallows was hijacked. Government never took delivery and Chiswell never got payment for them. This picture suggests they ended up being used by rebels for extrajudicial killings. This poor lad, Samuel Murape, was in the wrong place at the wrong time. British student, gap year, out there to visit family. It’s not particularly clear,” Layborn said, “but see there, just behind his foot—”

“Yeah, that could be the mark of the white horse,” said Strike.

Robin’s mobile, which was switched to silent, vibrated in her pocket. She was waiting for an important call, but it was only a text from an unknown number.

I know you’ve blocked my phone, but I need to meet you. An urgent situation’s come up and it’s to your advantage as much as mine to sort it out. Matt

“It’s nothing,” Robin told Strike, returning the mobile to her pocket.