A new witness comes forward with information about one of the country's most controversial murder cases. Now the police decide it's time to open their files and review the case. This is the story of what started as a routine call to a house fire but became the biggest murder investigation in Welsh history.

Twelve months into the investigation of who committed the Clydach Murders, the police face an extraordinary set of circumstances. The prime suspect, one of the victim's lovers, is a former police officer whose husband is a serving police sergeant and whose identical twin brother was the first senior police officer on the murder scene. How will detectives investigate three of their own?

The discovery of the owner of a gold chain found at the murder scene leads detectives to a new suspect: David George Morris. He is well known to the police, with a long criminal record. This is the breakthrough the police needed, and the scene is set for one of the most high-profile murder trials in Welsh history, but some in the community question if it is all a bit too convenient.

In the eyes of the legal system, David Morris is as guilty as guilty gets. But many locals still question if the right man is behind bars.