S2·E4 Sharp Compassion

The suspicious death of a hospital patient leads to post mortems being conducted on other patients who supposedly died of natural causes but now appear to have been murdered. Tony suspects the killer may be a person who believes they are releasing the victims from pain by their actions, guided by religious motives. However Islamic terrorists are also suspected, leading to the involvement of MI5. Carol is under scrutiny and needs Tony's help to keep her job.