Professional contract killer Alex Carter's carefully constructed life begins to unravel when his former colleague Cole Knight is discovered strangled and partially decomposed behind an industrial waste bin at the back of a forgotten alleyway, in a secluded, orange tree lined street in Madrid.Under instruction from the British government, and in collaboration with Alex, case handler Paul Fieldman begins to investigate the mysterious circumstances of Cole's murder, only to discover that the truth behind his assassination is much more disturbing than anyone could have ever imagined.What becomes clear for them both, is that in a job characterized by death, it's better the devil you know, than the devil you don't.