Alec is in jail after his arrest for murder, but he still manages to unnerve Emma. Rebecca and Sutton formulate plans for the Mercer family.

Sutton steps up her plans to win back Ethan, and makes a point to let Emma know her intentions. Feeling left out of Emma and Thayer's growing closeness, Mads visits her father in prison and shocks Emma with a family revelation. Dan continues his investigation into Derek's murder, regardless of Alec's arrest, and Jordan starts at his new school and tries to get close to Laurel.

Emma learns more about what happened the night Sutton's car went into the lake, raising her suspicions about whether her sister has been truthful. Ted invites his family to be his guests at an event in his honor and Rebecca orders Sutton to use the opportunity to further their plans for the Mercer family. Meanwhile, Emma heeds Laurel's romantic advice and Rebecca and Alec engage in a game of cat and mouse against each other.

Emma and Thayer further their investigation into the twins' birth mother and what Sutton may know about her. Laurel begins to suspect that something is not right with her sister and makes everyone nervous when she starts asking questions. Using ammunition provided by Rebecca, Sutton lashes out at Kristin during what is supposed to be a peaceful Mercer family dinner.

The Flipside Formal offers Emma the chance to try and trap Rebecca and Sutton in a lie, but she needs Ethan's help to pull it off. Laurel struggles with where her loyalties lie, while Kristin makes a troubling discovery that has more significance than she realizes. Jordan continues to waffle between Laurel and Mads, and Theresa's defense of Alec threatens to drive a wedge between her and Dan. Meanwhile, Rebecca and Ted, and Alec and Kristin, each reminisce about old times.

Emma struggles to make sense of newfound revelations and shifts in her relationships with Ethan and Thayer. After hearing Emma's suspicions about Rebecca, Sutton's faith in her mother begins to falter and she decides to take matters into her own hands. Rebecca is thrilled when Kristin and Ted's marriage continues to unravel, putting her one step closer to achieving her goal. Meanwhile, Alec realizes that Jordan could be a strong ally in his private war with his wife.

Everyone gathers to celebrate Dan and Theresa's wedding but the celebrations do not go off as planned. Ethan figures out who Emma is protecting and confronts her about shutting him out. Sutton's sudden change of heart confuses Emma, who isn't sure she trusts her sister. Ted's behavior grows more erratic as his family continues to fall apart. Meanwhile, in the game between Alec and Rebecca, Jordan decides whose side he's on.

Ethan's confession to Dan threatens to shatter the brothers' relationship forever. Sutton receives a mysterious phone call that may provide some valuable information. Emma's feelings for Thayer are tested when she finds herself in close quarters with Ethan. And someone else comes face to face with Emma and Sutton.

Growing suspicions have everyone on edge. Dan gives Ethan an ultimatum with heartbreaking consequences and Emma finally confronts Rebecca.