A man is lured to a sting by paedophile hunters. A few days later, a pensioner is found badly beaten. Cameras follow every twist and turn of an emotive and troubling police investigation.

Detectives investigate a man who they believe has brought a young woman into Britain unlawfully, on a one-way ticket from Bulgaria.

The police receive a call from a young man claiming that there are body parts buried in the garden of a house on an estate in Luton. A search team is dispatched but they face a wall of silence at the scene. Detectives suspect that it is a fantasy but, more worryingly, they may be being deliberately drawn into a long-running and brutal tit-for-tat gang war. Cameras follow every twist and turn of the case as it escalates further when the mother of the young man is stabbed in the chest. Police begin investigating the case as an attempted murder. This is real-life crime drama at its most intense.

A teenager is rushed to hospital with serious injuries that suggest she's been tied up and assaulted. She says she got them during sex with her boyfriend. But then she disappears from hospital...

A woman calls the police to a block of flats in Luton, where a bloody hand print is found on the wall, and a disturbing case unfolds.

A man lies dying in the street from a stab wound to his heart. A friend at the scene is desperate to find out if he will survive, but it's now a crime scene and he's not allowed to see the victim. Paramedics can't save the man so the police begin a murder inquiry, and they believe the friend may be able to tell them what happened. But they know that without his co-operation they may struggle to prove their case. Cameras follow in intimate detail a tragic case with a surprising and disturbing twist. This is real-life crime drama at its most intense.

This episode has unprecedented access to a major covert surveillance operation, which culminates in 10 simultaneous armed dawn raids against organised crime gangs.

A woman's body is found in overgrown grassland. When detectives inform her partner of her death, his behaviour marks him out as the chief suspect.