After the murder of a young mother in London, there's a climate of fear, and catching her killer becomes a national obsession. So police devise a controversial honeytrap fronted by a female officer.

Covert officer 'Lizzie' meets suspect Colin Stagg face-to-face and attempts to earn his trust. But as the weeks pass, the pressure she's under starts to take its toll.

While Colin Stagg is on remand in prison, another horrific murder occurs with some clear similarities. Is Stagg in fact an entirely innocent man?