Guest Stars Anna Maxwell Martin as Kelly Major Amanda Payton as Dr. Alison Parfit Rosie Cavaliero as DCS Dennett Michelle Greenidge as DS Judith Papastathopoulos Tracy-Ann Oberman as Helen Chalmers Richard Gadd as Liam Cleasby Michael Armstrong as Officer Mike Vinette Robinson as Professor Sarah McAllister Sasha Behar as Elizabeth Churchland Bleu Landau as Reece Greg McKenzie as Reporter Idris Balogun as Courier