When Scotland Yard intercepts a massive heroin shipment, British diplomat Ian Porter (Dougray Scott) is the prime suspect, thanks to his known association with notorious drugs trafficker, Krousov. Yet when an attempt is made on Porter's life, the strange behaviour of both Porter and MI6 leads the Yard to a staggering conclusion: Porter is not simply a British ambassador to Tajikstan but an MI6 operative sent undercover to expose Krousov's terrorist contacts. And when a Cold-War nuclear bomb goes missing, the race is on to uncover Porter's involvement and prevent a global disaster, with or without MI6's help. In the murky world of the Secret Services, nothing and no one are as they seem.