A family refuse to accept son Jack died of an overdose, and undertake their own investigation. They identify a man with him the night that he died. Dots then connect four murders...

Alan Jermey calls 999 to report that his home is on fire. When his partner Kirsty is found dead, he claims someone broke in and killed her. But evidence does not mount up in his favour. 

David Browning, a married father of two, confesses that he has killed his boss, Jill. But he claims that he is not guilty of murder, on the grounds of diminished responsibility. 

A 999 call comes in concerning a woman called Susan Nicholson. Her partner, Robert Trigg, says he woke to find her in a strange position and thinks she may have suffocated during the night after they fell asleep. The coroner agrees that she has suffocated, and records a verdict of accidental death. But things don't add up for Susan's family and they believe there must be more to the story. Her family discover this isn't the first time that Trigg has woken to find his partner has died after spending the night with him - history has repeated itself!

A panicked 999 call comes in from a man called Foster Christian, claiming he is being attacked in his own home. But later, survivor statements tell a very different story...

This true crime series uses the recording of a 999 call as the starting point to investigate a murder. Each episode focuses on a different crime but in each case the person who made the 999 call turns out to be the killer. Robert Brown, a veteran British Airways pilot, calls the police. After much coaxing, he reveals that there has been a very serious domestic incident with his ex-wife, Joanna, and that one of them has been hurt. Officers visit her cottage. But she isn't there, and worryingly, they find blood spots on the driveway. Brown is arrested and interviewed. After three days of interrogation, Brown's solicitor reads a prepared statement in which Brown confesses to having killed her by accident but the truth is far more sinister. Robert Brown attacked Joanna with a claw hammer, striking her 14 times while their children were in the next room. Despite evidence pointing to the fact that Brown had planned the killing for weeks, a jury found him not guilty of murder, controversially convicting him of manslaughter, meaning he would be automatically released in just 13 years. Joanna's family and friends mounted a campaign to keep him behind bars.