Newly promoted, Detective Sergeant William Warwick has been reassigned to the drugs squad. His first case: to investigate a notorious south London drug lord known as the Viper. But as William and his team close the net around a criminal network unlike any they have ever encountered, he is also faced with an old enemy, Miles Faulkner. It will take all of William's cunning to devise a means to bring both men to justice; a trap neither will expect, one that is hidden in plain sight...

William Warwick intègre la brigade des stupéfiants de Londres. L'équipe cherche à appréhender Assem Rashidi, surnommé la Vipère, un dangereux trafiquant. Alors qu'il prépare son mariage avec sa fiancée Beth, William est rattrapé par son ennemi Miles Faulkner, toujours en liberté. William élabore un stratagème pour traîner Miles et Assem devant la justice.