Tensions run high between sisters Tegan and Sara on their first day at a new school; their relationship became fractured during the summer because Tegan felt cast aside by Sara and their shared best friend Phoebe.

Sara continues to withdraw from her family, especially her mom; she and Tegan make progress with friends at their school and are invited to a party; as Tegan begins to make friends of her own, Sara realizes how important Tegan is to her.

As Tegan becomes closer to Maya, she gains more perspective on her relationship with Sara; Tegan feels responsible for Sara and it starts weighing on her heavily, especially compared to her friendship with Maya, which feels so easy.

After a turn in her relationship with Phoebe, Sara is in a serious funk and can't stop feeling sad; to distract her, her new friends decide the best way to cheer her up is to take her to a rave which gets a little weird.

As Tegan and Sara begin writing songs together, they start to bond and grow closer in a way they haven't been all year; this complicates Tegan's relationship with Maya, as Tegan chooses to spend more time with Sara than with her.

Tegan tries to repair her friendship with Maya; Tegan and Sara perform their songs in front of more people.

Tegan and Sara prepare for their first live show at a party, but a secret threatens to ruin everything; Sara feels awkward after her fight with Patrick; Tegan gets closer to Cass while missing Maya.