Joanne Froggatt's 'Dark Angel' gets American premiere date -- May 21

April 1 (UPI) -- PBS has announced May 21 as the American premiere date for the British television movie Dark Angel.

"Downton Abbey's Joanne Froggatt portrays the mother, wife, and infamous Victorian serial killer Mary Ann Cotton in Dark Angel, a one-night, television event coming to Masterpiece," PBS said in a Facebook post Friday.

Co-starring Alun Armstrong, Jonas Armstrong and Penny Layden, Dark Angel initially aired last fall on the Britain's ITV.

"Dark Angel is an extraordinary and chilling true story," ITV's controller of drama, Victoria Fea, said in June when the program was announced.

"We're delighted to have an actress of Joanne Froggatt's caliber in the lead role. The combination of a tautly written script, an outstanding cast and great producers in World Productions make this a really exciting addition to the ITV drama slate."