The City of Lies by Michael Russell
An IRA attack leaves two guards dead on the streets of Dublin. Two days later, a battle between warring gangs erupts at a race meeting, and on Ireland's east coast the cremated bodies of a wealthy family of five are found in their shuttered, burned-out villa.
Dispatched from Special Branch to investigate, Detective Inspector Stefan Gillespie soon finds himself caught in a web of Irish, British and German Intelligence - all playing against each other, all watching each other, and all plagued by rogue operators they can't quite control, as the certainty grows that Hitler is about to invade England.
And then, Stephen is sent to Berlin on a sensitive mission. His journey home becomes a dangerous pursuit in which no one can be trusted and the information he carries puts his life on the line.