Anna Maxwell Martin Theresa Actor Rachael Stirling Helen Actor Peter McDonald David Actor Rhashan Stone Fraser Actor Jonas Armstrong Gareth Actor Jodie McNee Jean Actor Ken Nwosu Eddie Actor Jim Howick DS Robin Parks Actor Amelie Bea Smith Eva Actor Fraser Holmes Ben Actor Tia May Watts Georgina Actor Julie Barclay Ana Actor Dan Burgess Jeremy Actor Elèna Gyasi Stephanie Greenford Actor Sophie Petzal Screenwriter, Executive Producer Carolina Giammetta Director Catrin Lewis Defis Producer Sarah Warne Music Jonathan Fisher Executive Producer