A mysterious illness draws Merlin to a distant village as the magical drama continues. But it soon becomes clear that there is more at stake than just his well-being as something sinister turns the air sour. Far from home and with no one to trust, Merlin becomes embroiled in a deadly game of cat and mouse. No longer sure who is the hunter and who is the hunted, can the young warlock survive long enough to uncover the truth?...

Elders of Longstead ask Merlin for help when their village is blighted by a mystery illness. The wizard sets off with Gwen and the knights but his spells appear to have no effect on the sick. Outside the village the knights find a girl Lamia encircled by bandits. After fighting to save hear they start to argue with each other and when Merlin sees Lamia eyes turning green he suspects shes not what she seems. Arthur leads a search party when the group fail to return to Camelot and Gaius discovers Lamia is indeed a sinister creature.