Dominic West has signed up to star as Fred West, who was charged with murdering at least 11 girls, and burying many of their remains at his home in Gloucester, England in the 1970s, while Watson plays voluntary worker Janet Leach, who sat in on police interviews with the killer.
Fred West committed suicide while awaiting trial in 1995 and his accomplice wife Rosemary is currently serving a life sentence for her part in the gruesome crimes.
The families of West's victims have voiced concerns the dramatisation will drag up terrible memories about the murders, but Watson has moved swiftly to reassure them about the nature of the show, which is set to air in the U.K. later this year (11).
She tells Britain's Daily Telegraph, "It is handled very sensitively. It is really about the investigation and the interviews. It's only indirectly about what happened."