Devil-worshipping Lucien Burgess abducts young mother Kirsten Ross from her house,leaving satanic messages in blood on the walls. Rose Teller links this to the similar disappearance and murder of Grace Allen, ten years earlier,the blood being identified as Grace's. Burgess was implicated but had to be released after undercover cop Richard Henley pulverised him. Luther locates Kirsten to a boat,where her dead body is found in a freezer and takes unorthodox action to trap the killer. Mark North is attacked by a gang of girls led by Alice and assumes Luther was behind it. He makes a complaint but Alice gets him to drop it by telling him she did it to get Luther back with Zoe.As a result Zoe offers Luther an olive branch ...and a little more.