Season 4

After a fire breaks out at a home, police receive a strange phone call that triggers a hunt for a killer.

The case of John George Haigh, who came up with a plan for the 'perfect' murder when he was serving time in prison for fraud.

When Pierre LeGris reports his wife Rui Li missing, police are instantly wary, and they uncover a tangled web of loyalty and deception.

Investigating the murders of two elderly women, a decade apart.

The murder of a part-time actress triggers a nationwide manhunt for a killer.

When Linda Anders is found dead at home, her wheelchair-bound husband Malcolm claims an intruder broke in. Police findings quickly change the course of the investigation.

Dismembered bodies of two women are both found in car boots, the first at a train station, the second in a city.

The case of John Bodkin Adams, a trusted GP who befriended older patients and was often named in their wills after their deaths.

The case of Robert Henry Davies, who committed murder after a sexual assault investigation threatened to revisit sins from his past.

The case of Charlotte Pinkey, a woman who disappeared in Ilfracombe after going to a party and never returning.