1. Luther, still plagued by the death of Zoe faces a serial killer wearing a Punch mask and tries to rescue an old acquaintance's daughter from the dangerous world of drugs and prostitution.
2. Luther must rescue Ripley before Cameron sets out his final murdering piece; schoolkids that are set to be dumped and gassed. Meanwhile, Jenny's ruthless and vengeful boss is demanding compensation for stealing her protege.

In 1994, 13 year-old Nicholas Barclay disappears from his home in Texas. Three years later he is found in Spain, disorientated and quivering with fear. His family is overjoyed to bring him home. But all is not what it seems. Whilst he bears many of the same distinguishing marks and tattoos, the boy looks decidedly different and now speaks with a strange accent. Why doesn't the family seem to notice these glaring inconsistencies? It's only when an investigator starts asking questions that this find out more...