The team reinvestigates the unsolved murder of 23-year-old Maureen Mulcahy of Port Talbot. After a major breakthrough, the team identifies a new prime suspect.

Six-year-old Carol Ann Stephens was abducted and murdered in 1959. Her killer was never caught. The Dark Land team comes across new evidence that could finally put this case to rest.

Muriel Drinkwater was brutally murdered near her home in 1946. The team finds a vital new clue that could be the missing piece of this tragic puzzle.

The team attempts to use comparative forensic analysis to solve the gruesome Brighton Trunk Murder, drawing on what they already know about the death of Mamie Stuart in 1919.