Helen is a mother of twins and wife to Wallace Webb, the UK government minister for defence.
Buchan is also a screenwriter and his debut TV seriesPassengeraired earlier this year on ITV.
Shes joined by Ella Lily Hyland as fellow psychopathic killer Williams.
Litvinenko,Chernobyl,The Lazarus Projectand stage actor Sam Troughton plays UK government Commissioner Stephen Yarrick.
Comedian, multi-hyphenate and household name Tracey Ullman plays the mysterious matriarch Alex Clark.
Save Me,Boiling Point, Moonflower MurdersandLivings Thomas Coombes plays tabloid journalist Philip Bray.
Soon-to-be Targaryen prince inA Knight of the Seven KingdomsFinn Bennett plays Kai-Mings American boyfriend Cole Atwood.
Bennetts also recently been inTrue DetectiveandDomina.
All episodes ofBlack Dovesseason one are streaming now on Netflix.
