Just streets away from the neon lights and fairground rides of Blackpool, police rush to the scene of a fire in an alleyway and make a grim discovery; the burning body of a teenage girl.

She's identified through DNA as missing 16-year-old Sasha Marsden, the brutality of her murder shocks even hardened detectives. Sasha hasn't been seen since being dropped off in the city centre for a new cleaning job at a hotel, but after finding sinister social media messages police discover things aren't what they seem, they're convinced she has fallen prey to a dangerous predator that if not stopped, will strike again.

The killer thinks he can outsmart the police, but forensic experts uncover a trail of hidden evidence to give detectives the advantage.

When a 72-year-old woman is found dead in her bed, police find DNA evidence linking a suspect. With no confirmed cause of death, they turn to advanced forensics to uncover the truth.