Victims and perpetrators reveal shocking details of lives consumed by stalking. It's a crime, often driven by a mental fixation making it particularly hard for victims to escape.

Incidents of stalking have doubled in the last year in the UK, with life-changing injury resulting 30 per cent of the time. Stacey Dooley talks to both victims and perpetrators, and spends time with police on the ground, including when they make arrests. Should the stalkers be in prison, or in therapy? Episode 1 focuses on ex-partner stalking, the most common form, while episode 2 focuses on stranger stalking.