After rescuing him from Mathias' clutches, Andromeda decides to show Lockie why he was really brought to St Kilda, though once again things take a turn for the worst. With his relationship with Wee Mary remaining frosty, Lockie takes some time to bond with some of the other island residents, much to Mathias' distaste.
As Andromeda's condition continues to deteriorate, the rest of the islanders take part in a scavenger hunt that they hope will lead to the Sigh - and Andromeda's cure. Tensions run high, lives are at stake, and familial bonds are tested as Lockie and the Hirtans prepare to make the ultimate sacrifice.