IT WAS HIS third meeting with his source, Earl Grey, in under forty-eight hours. The man was spilling secrets and the Service was haemorrhaging cash – Luke had twice had to contact London to get pre-authorization for money transfers to Janulis’s nominated bank in Helsinki. But, so far, the feedback from Vauxhall was encouraging. The raw intel, the so-called ‘CX’, that Luke was sending back was getting fast-tracked to the reports officers for cross-checking. They liked what they were reading, Luke was told, but they had one concern. The Service placed a huge amount of trust in its agent runners, but Earl Grey’s greed was just starting to raise suspicions. Could he be embellishing what he was delivering in the hopes of earning more of the filthy lucre?

People defect or become agents, betraying secrets, for any number of reasons. It can be personal: a growing, festering grudge against the state or a colleague. It can be ideological: a sometimes starry-eyed belief that Britain, or wherever, is some kind of utopian paradise compared to the flawed purgatory they are living in. It can be hideous disillusionment: the belated discovery that life in whatever country or organization the agent is in is not what they thought, and they want out. But often, more often than people realize, it comes down to plain old money. And Darius Janulis, ‘legals officer’ at Matulis ChemExport, and designated SIS human informant, wanted lots of it.

They sat on a bench in Bernardine Park, between the banks of the River Vilnia and the ochre walls of Vilnius’s Old Town. It was a spot Luke had chosen where it would be exceptionally hard for anyone to overhear them. Janulis appeared to have overcome his earlier nervousness, perhaps soothed by the thought of all the cash flowing into his numbered account in Finland. In return, Luke was extracting from him every last item of intelligence on WaffenKrieg90, its twisted worldview and, crucially, what his US military counterparts in Afghanistan would have called its TTPs – its tactics, techniques and procedures.