Guest Stars Jack Bannon as Sam Thursday Hermione Corfield as Cassie Watkins Stefanie Martini as Georgina Mortmaigne Milo Twomey as Dr Hector Lorenz Hugh Simon as Professor Kemp Darrell D'Silva as Geoff Craven Ben Lambert as Guy Mortmaigne Rob Callender as Philip Hathaway David Burnett as Ricky Parker John Draycott as Turnbull Peter Forbes as Hodges Amy McCallum as Julia Mortmaigne Eleanor Williams as Ingrid Hjort Sam Coulson as Mark Bryden