After the alleged suicide of her priest brother, Grace travels to the remote Scottish convent where he fell to his death. Distrusting the Church's account, she uncovers murder, sacrilege and a disturbing truth about herself.
| Actor | Role |
|---|---|
 Jena MaloneGrace | Grace |
 Danny HustonFather Romero | Father Romero |
 Thoren FergusonDCI Harris | DCI Harris |
 Will KeenJohn | John |
 Ian PirieVincent | Vincent |
 Janet SuzmanMother Superior | Mother Superior |
| AAlexandra LewisSister Beth | Sister Beth |
 Steffan CennyddMichael | Michael |
 Kit RakusenYoung Michael | Young Michael |
 Eilidh FisherSister Meg | Sister Meg |
 Jolade ObasolaSister Matilda | Sister Matilda |
 Victoria DonovanGrace's Mother | Grace's Mother |
 Shaun ScottFather Carol | Father Carol |
| GGodwin ToPatient's Husband | Patient's Husband |
| DDaisy AllenYoung Grace | Young Grace |
| MMarilyn O'BrienNurse | Nurse |
| VValerie SarrufFemale Patient | Female Patient |
| BBrian WellsTaxi Driver | Taxi Driver |
| MMichael BrophyFather Jacobs | Father Jacobs |
| CCharlotte PalmerSister Dianne | Sister Dianne |
 David BoyleAdoption Clerk | Adoption Clerk |
| HHelen AyreNun | Nun |
| KKibibe BaileyNun | Nun |
| JJanlyn BalesNun | Nun |
| RRachael Joanne BrownNun | Nun |
| RRuth ConnickNun | Nun |
| LLouise CowenNun | Nun |
| JJennifer DexterNun | Nun |
| LLiz HarcaNun | Nun |
| AAmanda HeiberNun | Nun |