Preview: Deceit

Niamh Algar plays the undercover Sadie who leads a double life. Photo: Channel4

In the final episode of this four-part drama, based on a 1992 true story, Colin Stagg (Sion Daniel Young) is implicated in the murder of Rachel Nickell; but another horrible attack in south London occurs whilst he awaits trial.

Psychologist Paul Britton (Eddie Marsan) is called in to assist with this new case, having already played a large role in the case against Stagg. The similarity of the two crimes perplexes the police, and destabilises undercover officer Sadie Byrne (Niamh Algar).

The evidence against Stagg is far from watertight, and everything comes to rest on the evidence collected by Sadie, codename ‘Lizzie’, while undercover. Is he innocent or guilty? The verdict has not yet been returned, and so the series concludes with many long-awaited questions answered.

Deceit – Friday at 9pm on Channel 4