A former war hero is arrested for the shooting of a police officer, but claims to have been set up by a man who has stolen his identity and is determined to destroy him. The newly-established Identity Unit identifies two similar cases, and DI John Bloom becomes convinced that the identity thief is punishing his victims for their marital indiscretions.
Immigration records show a woman entering the UK hours after she was cuddled in Australia. DI Bloom realises that the impostor is working out unresolved childhood issues, and that she may pose a threat to her father and his fiancee. DS Wareing is unsettled by Bloom's cavalier approach.
The Identity Unit must protect a woman when her true identity as the wife of a convicted child murderer is exposed. DI Bloom abandons the safe house when his lover, Adile, asks for his help, and the woman's son is kidnapped, forcing the Identity Unit to find a way of meeting the ransom demand.
A dentist claims that an important Asian businessman is an impostor, and the Identity Unit is tasked with confirming his true identity. DI Bloom is sent under cover to obtain a swab for DNA analysis, but his cover is cmpromised.
A routine DNA sample identifies a woman as a terrorist who has been on the run for 25 years. The Identity Unit is tasked with obtaining a confession to her involvement in hug, but she absconds with her former accomplice. The officer who led the original investigation is brought in to assist, but it soon transpires that he has been keeping a secret all these years.
DI Bloom's secret life as Brendan Shea is exposed when Atif's body is discovered and Adile is brought in for questioning. When her father kidnaps Det Supt Lawson, Bloom has to decide where his priorities lie.