As the pieces to Bellevue's central mystery begin to fall into place, every step Annie Ryder (Anna Paquin) takes toward the truth also leads to her reckoning.
With Maggie Sweetland out of commission following her drug overdose, Annie must turn to the one place she's never dared to look for clues to Sandy Driver's (Angela Magri) murder — her father's case notes.
When she examines them, she finds that the last page is missing. She later finds out the page covered a 911 call made two days before his death.
Later, Annie listens to 911 calls from that day and discovers one from Mayor Lily Mansfield (Janine Theriault), a teen at the time, claiming a stranger broke into her house and left fingernails on her bed. Presumably, they are Sandy Driver's fingernails.
After finding old interview footage from Sandy's investigation, Annie finds one of Lily Mansfield, who flirts with the interrogating officer to dodge his questions about Sandy's disappearance. Annie begins to suspect Lily and her father may have had an affair.
Annie visits the Christmas pageant coordinator, who commented earlier about Lily's past. She reveals that Lily had an abortion when she was younger, after an affair with "an older man."
Annie goes to Peter to ask if Lily and her father were together at the time of his death. She believes her father did not process the scene the night of the 911 call, but he found something that encouraged him to stop looking for Sandy's murderer. It made him go crazy. Annie decides to digest the information at her father's old fishing cabin, where he ended his life.
Annie listens again to the 911 call and comes to a realization. She confronts Peter about the fact he knew about Lily finding fingernails on her bed, something Annie never told him. He confesses he was the officer who responded to the 911 call. At the time, Lily begged him not to process the scene, then she grabbed the fingernails from him and flushed them down the toilet. Afterwards, she seduced him.
Stunned by the revelation that her mentor helped hide evidence from her father, Annie reaches her breaking point. That night, she finds Eddie (Allen Leech) at a barbecue with Briana (Amber Godlfarb) and daughter Daisy (Madison Ferguson) and becomes jealous as they act like a family.
Annie explodes on Eddie and says she wants him back, but he rejects her claiming he likes being normal with Briana. Later, Annie exchanges harsh words with Briana, which Daisy accidentally hears, and then she kisses Brady (Billy MacLellan), leading to Brady and Eddie getting into a fist fight. After Daisy rejects her mother's plea to go home with her, Annie walks away upset.
Later, Peter stops by Lily's house and confronts her about the fingernails. She claims she has no idea who left them at her house. He tells Lily he blames himself for his partner's death and for ruining Annie's life, while also trying to end things with Lily. But she begs him to stay and they sleep together.
A drunken Annie unravels at her father's cabin. She attempts to hurt herself, but she is stopped by a man who holds a very close resemblance to her father. He runs away before she can ask who he is.
The shocking episode ends when Annie walks back into the cabin and sees markings on the wall showing her growing progression as she got older. She then sees that closer to the ceiling there's another marking for "Adam, 16."
Bellevue airs Tuesdays at 10 p.m. ET on WGN America.