Billie and Justin struggle to explain the world of the lake to Naomi and Oliver when they arrive early to collect Billie. Over the Labour Day weekend Billie and Justin seek closure with their friends and enemies, Justin and Maisy face off for the last time to determine who walks away with the cottage of their dreams.

Faced with the murder cabin being sold, Justin decides to reveal the Trust to Maisy with an offer to dissolve it in exchange for a buyout. Never one to compromise, Maisy strands herself and Justin on a floating dock until they can come to a new agreement. Meanwhile, Billie and Killian go on a psychedelic quest for contraceptives, and Victor grapples with body issues.

Excited that Billie’s surprise visitor is her birth mom and his teenage best friend, Justin wants nothing more than to spend time with them. Problem is, he’s firmly in the doghouse after Maisy’s cookout. Exiled and adrift, Justin finds himself drawn into helping with Opal’s drag routine for the Boathouse Talent Show. Teesa signs up Billie and herself for the the show and explore the past.

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.

While the adults are at the Boathouse euchre tournament, Billie, Killian, and the Quads decide to pass the rainy afternoon with a Ouija board. Things get weird quick with the disappearance of Olive and the appearance of crossbow-wielding cultists. With a serious lack of common sense among the remaining Quads, it’s down to Billie’s horror movie knowledge to get the teens through this nightmare.

Justin crashes Jayne’s Aqua Spin class to interrogate arson suspects. Billie is torn between her personal and professional life, and Maisy uses a “spa day” to extract medical samples from Mimsy.

An opportunity arises for Justin to redeem himself when he discovers the Boathouse fire may have been the result of foul play. Meanwhile, Billie’s eco-ideals are challenged by a magnetic nemesis and Maisy tries to prove her mother is lying about her imminent death.

Justin brings Billie, the daughter he gave up for adoption, to the lake where he spent summers as a boy. Billie is determined to return to the city, but a new friend could change her resolve. A revelation about their former family cottage gives Justin a new purpose.

Justin makes a deal to obtain evidence that could prove his arson theory while Billie struggles to adapt to the harsh physical demands of tree planting. Meanwhile, Maisy attempts to draw out her mother’s lies with a boring AGM, but nothing seems to crack Mimsy’s veneer.

Justin and Riley’s relationship is put to the test after a spontaneous wedding goes awry and Billie makes a daring decision that could risk a prestigious internship that awaits her in the city. Meanwhile, Maisy reckons with life-changing news about an old enemy: her mother, Mimsy.