When Detective Inspector Robert Finlay is sent to a military barracks to investigate a connection to weapons discovered in the possession of London gangsters, he is given strict instructions not to get involved in a suicide enquiry into the recent death of a young, recruit soldier.

The army partners Finlay with Floria McLaren, an ambitious military policewoman who doesn't believe the death was a suicide. Ellie Rodgers is a traumatised army officer who discovers the existence of a cabal of soldiers who exploit young recruits for sexual and criminal purposes. Jodie Baker is the plaything of a devious and narcissistic training sergeant. Wendy Russell is a senior police officer with an undercover agent gone missing. All are in danger. Separately, or together, they must fight for justice.

What appears to be a routine investigation soon takes on a life of its own as Finlay finds himself in a struggle with powerful forces – both criminal and from the military establishment – who know that, inside the wire, they make the rules.