Following the accidental discovery of a "head" afloat on the Regent Canal, London, PI Dr Jake Flintlock is seduced into taking on a case which draws him to Northern Spain and its darker history. There, in the company of his sidekick Dr Bum Park, Jake faces a mystery wherein an ancient Basque legacy of vengeance and strife intersects with a private vendetta — one with Jake himself as its unwitting target.