Police drama series. Oxford's last surviving all-female college is bidding farewell to one of its most prominent professors. But during a reunion of her brightest students, one of the group, Poppy Toynton, is found murdered at the bottom of a flight of stairs. Lewis is convinced that the death is somehow connected to an attack ten years ago which left the 15-year-old sister of another of the group, Ruth Brooks, in a coma. Lewis gets in touch with his former DS, Ali McLennan, but she is adamant that the old investigation was put to bed. The police believed Ruth's ex-boyfriend attacked the girl, then used his family's money and influence to escape justice. When another student is killed, Poppy's co-workers discover that Poppy had been carrying out a hate campaign against two of the women who lived with the professor during their time at the college. But when Ali McLennan becomes the latest victim, Lewis and Hathaway are drawn even deeper into the mystery of the college and its secrets.