Justin and Billie trap all the suspects on a pontoon boat to clear his name by exposing the identity of the Boathouse arsonist. Keen to get to the tree planter's farewell party before Ivy and Forrest leave, Billie agrees to help Justin. Maisy finally accepts her mother's diganosis and decides to make peace before the summer ends.
Justin returns from living abroad after a break-up with his long-term partner, in the hope of reconnecting with the biological daughter that he gave up for adoption in his teens. His plans to create new memories with his city-loving daughter Billie at the idyllic lake from his childhood go awry when he finds out his father left the family cottage to his 'picture-perfect' stepsister, Maisy-May.