The clock rolls back to the first days aboard Fulmar's Folly. Adrift in a nautical apocalypse; Jack and Sam attempt to shield the children... as the world slowly eats itself alive. In the present day: Something’s clearly wrong with Arrietty.

As Fulmar's water supply runs out - Lina makes a desperate play for the backpack she left on shore with dire consequences. Arrietty is horrified when the female Wasting does something that changes everything.