Forensic pathologists Professor Leo Dalton, Dr Harry Cunningham and Dr Nikki Alexander are back in one of the BBC's most successful and longest-running crime dramas. Series 11: This series kicks off with an RAF helicopter crashing into an asylum seekers' detention centre. Harry suspects a possible RAF whitewash and finds himself up against the Ministry of Defence who are struggling to cope with the demands of the wars in Iraq and Afghanistan. Subsequent stories include a trail of murders that leads to a hospital cover up, and the killing of a notorious female murderer that forces Nikki to revisit an emotive and controversial case from her past. Series 12: This series starts with Leo arrested for drink driving and finding himself doing community service on a rough London estate where gang violence among kids is common. When Nikki investigates a murder of a young girl from the same estate, Leo finds himself in the midst of a turf war. Elsewhere Harry mentors an eager medical student who seems more interested in the media frenzy over his latest case than pathology, and Nikki investigates an armed raid on a terrorist cell, facing increasing police hostility to her investigation as she begins to suspect the victims are innocent...