On Valentine's Day 1988, a young girl is discovered brutally murdered in Cardiff's docklands. Despite evidence pointing to a lone white male killer a ten month investigation concludes with the arrest of five local black men. What happens next beggars belief.

Despite the lack of any forensic evidence tying the men to the crime, they are put on trial and face a marathon ordeal at court in what would become Britain's longest murder trial. Their fate rests on a police confession from one of the five men accused - but can this testimony be trusted?

With three of the men sentenced to life in prison, the families begin a campaign to have their convictions overturned. It soon attracts worldwide attention and begins to unearth some disturbing facts about the case. Meanwhile, the real killer is still at large, and one of the accused faces a threat to his own life.