Emilia Fox returns for series 18 of this compelling mystery drama in five thrilling two-part stories that shine a light on the city's dizzying extremities from the rich and the poor, to the powerful and the disenfranchised. In Sniper's Nest, London is under siege from a gunman who picks off its citizens at random, and Falling Angels tells the darkly moving story of two people drawn together after they witness a man being hit by a tube train. In Protection, a young girl vanishes without trace and Squaring the Circle pitches us into classic thriller territory as the team investigate...

Emilia Fox returns for series 18 of this compelling mystery drama in five thrilling two-part stories that shine a light on the city's dizzying extremities from the rich and the poor, to the powerful and the disenfranchised. In Sniper's Nest, London is under siege from a gunman who picks off its citizens at random, and Falling Angels tells the darkly moving story of two people drawn together after they witness a man being hit by a tube train. In Protection, a young girl vanishes without trace and Squaring the Circle pitches us into classic thriller territory as the team investigate a bloody shootout. In One of our Own, the murder of a rising police star triggers an intense and harrowing journey into police loyalty and familial betrayal while the team face down a brutal gang of drug traffickers.