May 1942. Thousands of American GIs are stationed across eastern England building airfields to bomb Germany. Cambridge is a 'liberty town' - a hot spot for Yanks on leave. DI Eden Brooke is called to the aerodrome five miles east of the city when the remains of an airman, identified by his dog tag, are uncovered as workmen extend the runway. It's clear the victim has been buried for decades. Brooke discovers the base was used to train US pilots in the Great War - a quarter of a century earlier. When another soldier's body turns up just days later, it's clear there is a connection. The clues all lead back to a long-lost parish register, and a story of love and revenge which spans two world wars.