LUKE CARLTON DRAINED the last of his coffee and tossed the empty cup into the bin. It was time to board the train to Cheltenham. A lot had happened in the few hours since he had walked into that early-morning meeting in Vauxhall Cross. The Svalbard outbreak had now been declared a Level One priority and an entire cross-agency team had been assembled at short notice, pulling in expertise from all three UK intelligence agencies: MI6, MI5 and GCHQ. They were tasked with uncovering everything they could possibly find out about the Moscow connection. For Luke, that meant an urgent visit to the West Country, to GCHQ, the Government Communications Headquarters, to get briefed on the SIGINT and cyber intercepts.

‘You’ll also be working with someone you know,’ Angela had told him breezily, as they filed out of the briefing room.

‘Who’s that?’

‘Jenny Li. From Snuffbox.’ Luke smiled at hearing the quaint MI6 slang for their sister agency, MI5, across the river. ‘She’s their CBRN specialist, remember? She knows more about chemical and biological weapons than anyone else in the agencies. C’s happy to let her be in the lead on this one so she’s running the show. Learn all you can from her. We need you to get up to speed on this pretty fast. Cabinet Office are demanding answers …’ She rolled her eyes slightly. ‘Like, yesterday.’

Luke remembered Jenny Li all too well from the Colombia op. They had had the shared experience of going into University College London Hospital to interview a man suffering the hideous effects of acute radiation sickness. Jenny, he recalled, could be quite condescending at times, but Luke was the first to admit she knew her subject inside out and was scarily well informed when it came to dangerous substances.

Jenny met him at the ticket barrier, wearing a white silk scarf and a fawn overcoat tied tightly at the waist. Luke could see she was scrolling through her phone messages while periodically looking up and scanning the crowd.

‘Good. You’re on time,’ she said briskly, putting the phone into her pocket. ‘Shall we go?’

As the Great Western Railway 12.25 to Cheltenham Spa slid westwards out of Paddington, Jenny folded her hands across the table between them and leaned towards him. Her dark hair was cut short, shorter than he remembered from last time, but it still framed her face, with her soft, hazel eyes, perfectly. Luke noticed a circle of paler skin on her finger where a ring might recently have been removed. He thought better of making any comment. She glanced once behind her, checking that no one else was in earshot, then looked Luke in the eye as she spoke. He had forgotten how intense she could be.

‘How much do you know, Luke, about Russia’s biological-weapons programmes, past and present?’ she asked him.

‘Not a lot.’