Scottish anaesthetist Mia Beaton arrives in New Zealand for sister Cassy's wedding, only to find Cassy has died. Mia determines to find her sister's killer among the unusual townsfolk.

Mia makes enemies as she lines up suspects. She discovers Cassy had secrets, leading to conflict between Ewan and Teddy - but little does she realise that Ewan has a secret of his own.

Mia questions Teddy and Harry, with conflicting results. An arson attempt fuels Mia's suspicions that she is not welcome. The realisation that she hardly knew Cassy draws Mia closer to Ewan.

The town's Whitebait Festival proves the worst possible drug comedown for a strung-out Mia. The truth about her deadly past in Scotland is revealed, yet she remains unrepentant.

With Sadie's help, Mia digs into an earlier death. Meanwhile, Annot recalls more of Ewan's misbehaviour than he would like, and a gruesome discovery in the forest puts Mia in immediate danger.

A deadly hike up the ridge reveals that Mia and Ewan have more in common than expected. While addiction may be a weakness, it gives Mia strength to bring down her sister's killer.