James Weber Brown as John Duval

Indira Varma as Dr. Catherine Benson

Dervla Kirwan as DI Jane Ambrose

Annie Cooper as Tobi Wright

Hugh Bonneville as Commander William Calthorpe

Tom Beard as Mr. Bowles

Susie Amy as Rosemary Calthorpe

Alistair Petrie as Lieutenant Charles 'Chuck' Carter

Elizabeth Healey as Rachel Garvie

Vicki Michelle as Mary Woodward

Angela Thorne as Mrs. Garvie

Cat Simmons as DC June Francis

Andrew Whipp as DS Pinker