Presented by actor and presenter Will Mellor, he covers seven new criminal cases to expose murderers, fraudsters, swindlers, sexual predators and drug dealers within the police force.
One of the UK's most prolific sex offenders ever, David Carrick took advantage of his position as a serving officer to attack women for nearly 20 years.
When police arrive at a devastating car accident, they find a young woman with horrific head injuries. But her fiancé, officer Martin Forshaw, is barely hurt.
A police car executes a stop and search on a drugs courier, seizing hundreds of thousands of pounds - but serving officer Kashif Mahmood then lets the driver go.
When royal protection officer Michael Coulton's wife is found murdered just yards from her work, a few of his secrets begin to come to light.
Australian officers couldn't believe it when they intercepted a call to an international drugs cartel and heard their senior officer Mark Standen on the line.
An unknown blackmailer laces dog food with poison and baby food with glass, always able to stay one step ahead of police - until his true identity is revealed.
When sergeant Drew Peterson's wife Stacy goes missing, he claims she's left him for another man - but it's then discovered that his ex-wife also died mysteriously.