In the opening of Episode 1 of Tell Me Lies Season 3, set in 2015, Stephen's call to Bree just as she's about to marry Evan reveals a shocking truth: the girl he cheated with was none other than Lucy. Meanwhile, in a separate scene, Lucy and Pippa, Bree's bridesmaids, discuss Stephen's past. Lucy brings up his name, and Pippa reminds her of all the pain and turmoil he caused her in college.
Lucy then confronts Bree, who leaves the waiting room in a panic. Lucy follows and finds Bree lamenting that she's a "terrible person," which confuses Lucy. The episode then takes us back to 2009, where Lucy and Bree wake up in Lucy's house after spending Christmas break together. Lucy and Stephen are now dating after his breakup with Diana. Bree assures Lucy that she won't judge her for getting back with Stephen despite his past misdeeds. Lucy is actually excited to see where things go with Stephen now that they are back together.
Meanwhile, Evan returns home from a trip and runs into Stephen. Stephen talks to Evan about Wrigley and asks if he's okay after the revelation of Evan's affair with Lucy. Stephen is actually uneasy about the idea of them hooking up, but he won't bring it up with Lucy unless she voluntarily confesses.
In another scene, Pippa and Wrigley return to campus, where Pippa is worried about him. Wrigley reassures her and thanks Pippa for being there for him. In their dorm room, Pippa meets Bree while Lucy is also present. The trio discuss Drew's death and Pippa asks Bree about Oliver. Stephen arrives to see Lucy, and the two leave together. Pippa and Bree comment on how odd it was seeing Stephen and Lucy together again. On their way to class, they run into Oliver, who casually wishes Bree a happy New Year.
Lucy and Stephen lay in bed, chatting about their friends' apprehensions regarding their reconciliation. Later that night, the group gathered at a party. Stephen made a comment about Evan in front of Bree, but she ignored it. Wrigley tried to procure MDMA and asked Evan to join him. Bree and Pippa offered to buy the drugs from Alex, hoping for a better deal, eventually acquiring six pills. As they rode in Alex's car, Bree wondered where she had seen him before.
Upon returning inside, Pippa ran into Diana and the two discussed Wrigley. Diana advised that MDMA was a bad idea for him given his mental health. Lucy and Stephen took a pill together, though Stephen secretly pocketed his. Pippa told Wrigley that he shouldn't take the pill, and although he was upset, he agreed. Pippa returned to her room and asked Bree and Lucy to keep an eye on him. After she left, Wrigley admitted that he had already consumed the pill.
As the drug took effect, Lucy, Evan, Wrigley, and Bree grew increasingly uninhibited. Stephen felt uncomfortable watching Lucy enjoy herself and asked her to leave with him. Outside, Bree smoked a cigarette as Wrigley joined her. They discussed the drug, and Wrigley claimed that he couldn't get high due to low serotonin levels, deciding instead to walk Bree back to her dorm.
Bree told him about her affair with Oliver, which shocked him. Their conversation turned serious as they talked about Drew's death. Wrigley admitted that he felt his parents blamed him, and Bree said she related.
She reveals that her mother was just 14 years old when she gave birth to her, and subtly hints that her father had physically abused her. The two bond over their shared trauma and eventually share a laugh together. Meanwhile, Lucy and Stephen are back in her dorm room, preparing for an intimate moment. As they are about to have sex, Stephen pressures Lucy to confess to sleeping with Evan. While under the influence of drugs, Lucy instead admits to asking Leo to choke her during their sexual encounters. Stephen reacts badly and suggests that he would date Bree in order to force Lucy to confess. Lucy refuses to say anything more, and Stephen goes to sleep without touching her. Lucy lies awake as the drugs wear off.
The next morning, Bree and Wrigley wake up at the bus stop where they spent the night. Sober and awkward with each other, they agree to keep what happened a secret. Lucy wakes up alone and tries calling Stephen. Bree arrives, and Lucy is distracted by an email from the university administration asking to see her. Worried, Lucy attempts to call Pippa, but Pippa ignores the call and instead meets Diana. She confronts Diana about encouraging Drew to return to campus, which led to his death. Diana refuses to take responsibility, and the two argue. Pippa admits that she can't stop thinking about Diana's comments and suggests that her feelings may be more than just platonic, leaving Diana unable to respond.
Meanwhile, Evan and Wrigley talk about Bree. Wrigley reveals that Bree was having an affair with an older, married man, which shocks Evan. Bree accompanies Lucy towards the admin office and goes to Oliver's office. She sees a young student leaving and follows her, realizing that Oliver is now involved. Evan later visits Oliver for career advice, and Oliver tells him to figure out what he wants once he is less hungover.
At the admin office, Lucy is questioned about the allegation that Chris sexually assaulted her. She refuses to discuss it and asks them to stop pushing her. Later, Wrigley opens up to Pippa about feeling like the person everyone worries about. Pippa encourages him to work on his creative skills. In her room, Lucy looks through old photos of herself and Lydia. Stephen shows up and confronts her about Evan. Lucy apologizes and insists it meant nothing. She begs for forgiveness, but Stephen tells her to take their relationship one day at a time.
The episode returns to 2015 as Bree reassures Lucy and Pippa that she is only nervous. Stephen arrives at the wedding with a date, while Wrigley and Diana sit separately. Bree walks down the aisle towards Evan, and the two are married as Lucy watches from beside her.
