The police have a serial killer on a murder spree numbering three victims in the last month. The frequency of his killing is increasing rapidly. The killer has been keeping mementos of his victims, jewelry that he's been giving to his wife. The women were all strangled and Luther correctly concludes there can be only one explanation for why attractive young women would get into a car with a stranger: he's a taxi driver. The theory is right, but the police arrest the wrong man and realize that getting him will not be simple. Meanwhile, Henry Manson, the man Luther may have beaten into a coma has woken up. He tells Alice Morgan of his dilemma and she decides to take action.
—garykmcd