Joanne Froggatt, who stole the hearts of millions of viewers as Anna, the loving and resilient lady’s maid in the beloved Masterpiece series “Downton Abbey,” stars in a totally different role in a spine-tingling drama coming to Masterpiece.

Dispensing death from the spout of a warm teapot, Froggatt plays the notorious poisoner Mary Ann Cotton in “Dark Angel.” The drama premiered on CPTV on Sunday, May 21, and is now available to stream for a limited time by clicking here>>

Directed by Emmy Award winner Brian Percival (“Downton Abbey”) and inspired by the book Mary Ann Cotton: Britain’s First Female Serial Killer by noted criminologist David Wilson, “Dark Angel” dramatizes the events that drew a troubled woman ever deeper into a career of casual murder, while her loved ones and friends, who were also her victims, never suspected a thing.

Born in North East England in 1832, a child of the coal fields, Mary Ann Cotton grew up in poverty with the dream of escaping the hard life of a miner’s family, a goal she came tantalizingly close to achieving. Her chosen means were her good looks, sexual allure, and the dirty secret of 19th-century suspicious deaths: arsenic, which is tasteless and easily disguised in a cup of tea.

A Golden Globe winner and three-time Emmy nominee for her “Downton Abbey” performance, Froggatt is joined by an exceptional cast, including Alun Armstrong (“Little Dorrit” and “Bleak House” on Masterpiece) as Mary Ann’s stepfather, Mr. Stott; Thomas Howes (“Downton Abbey” on Masterpiece) as her husband number two, George; Jonas Armstrong (Robin Hood) as her longtime lover, Joe; Sam Hoare (“Jane Eyre” on Masterpiece) as husband number three, James; and Laura Morgan (“The Hollow Crown” on Masterpiece) as her best friend, Maggie.

View the trailer: