Bad Blood

During a briefing, Agent Briggs and Agent Sterling argue about the case. Sterling admits that she knew it wasn’t a Masters case but pursued it to help a missing girl and teach Briggs about objectivity. Their clash exposes old fractures from a past case. Lia and Sloane intervene, and Dean steers the group back to finding Celine. Sloane realizes that Michael is no longer in Celine’s room, and Cassie admits that she left him there alone.

The team deduces that Michael has gone to confront Thatcher Townsend. At the Townsend home, they find Michael and Thatcher drinking. Using aliases, Lia and Michael provoke Thatcher, who targets Sloane, making remarks about her deceased brother. Michael accuses his father of hurting Celine; Thatcher denies it. When Michael taunts him, Thatcher backhands him, and the blow knocks Michael to the floor. Dean steps between them. Unconcerned, Thatcher offers his continued assistance and leaves.

Michael jokes to minimize the incident, while Sloane, shaken, clings to him. Agent Sterling calls, confirming that she watched the scene on camera. Cassie profiles Michael and realizes that he engineered the confrontation because he doesn’t believe that Thatcher hurt Celine. She proposes a new theory: Celine staged her own disappearance to see if anyone would notice that she was gone. The group accepts this as the most plausible scenario. Lia presses Michael about his feelings, and he retorts that his love for Celine predates his love for Lia.

The next morning, the team finds Celine alive on a dock. They fly home to Quantico in silence. Midflight, Judd gives Cassie a buried file on Robert Mills, an inmate tied to Redding. Mills was convicted of killing his ex-wife, Mallory, whose body was never found; Mills was later killed in prison. Judd explains that he approved the Celine case to support Michael, but warns Cassie that the Mills lead is dangerous and she shouldn’t pursue it alone.

At her mother’s grave, Cassie tells Dean she believes that Mallory Mills’s body, not her mother’s, is buried there. She profiles the Masters’ recruitment method: They target abused women and force them to kill the previous target to survive. She fears that her mother, Lorelai, survived by becoming one of them. While Dean supports her, Cassie remembers her mother’s promise and realizes that another witness might have the answers she needs.

Cassie and Sloane meet Laurel, Cassie’s half-sister, at a playground. Laurel keeps her distance but warms to Sloane through numbers. She says the swing chains she places around Sloane’s wrists resemble the bracelets her mother wears for a “game.” Laurel then reveals a second self, named Nine, who handles the game. Nine surfaces, threatens Cassie, and demands to see her blood. Sloane gently removes the swing chains, and Laurel returns. As they leave, Laurel hums a distinct seven-note tune and says the wheel always turns.

The Masters may come and go, but the Pythia lives in the room.

On the roof, Cassie tells Lia about Laurel’s split personality, created to survive trauma. Lia connects this to her own past, revealing that her given name is Sadie and that she survived a cult by separating Sadie, who performed the required role, from Lia, who learned the rules. The exchange sharpens Cassie’s understanding of how people use masks to endure. Their conversation ends when Celine arrives at the house.

Celine says she came for Michael’s birthday. Lia starts a game of Never Have I Ever to surface unspoken truths. The game confirms that Celine and Michael were never romantically involved and that Celine prefers blondes, glancing at Sloane. Celine admits that she faked her disappearance after a threat from Thatcher. When Sloane bluntly asks if she was born outside marriage, Cassie reads the pain in Celine’s face and deduces that Thatcher is her biological father. Michael declares that he’s taking everyone out to celebrate, using money from his new trust fund.

Michael rents an amusement park. In the house of mirrors, he tells Cassie he accepts that Celine is his sister and accurately reads Cassie’s distress about Laurel. Later, Cassie finds Sloane by the Ferris wheel, humming Laurel’s tune. Sloane says the seven notes fit a pattern and may encode something.

When they return, they find FBI vehicles and agents from Laurel’s protection detail. Agent Briggs confirms that someone abducted Laurel. An AMBER Alert yields nothing, and Agent Sterling investigates a possible FBI leak that exposed Laurel’s location. Briggs takes responsibility for bringing Laurel into the program. Cassie breaks down, blaming her visit for the abduction.

Laurel lies on a ritual altar. The Pythia, bruised, declares the child worthy. The Masters, including a senior member named Five, circle them. They then subdue the Pythia, chaining her to a wall to await another judgment.

In her room, Cassie panics about the test that Laurel faces. Sloane enters with an answer, having decoded Laurel’s tune. The seven notes map to an old Social Security number for a boy named Mason Kyle, whose records have been scrubbed. The only surviving record is a childhood photograph. The team concludes that Laurel identified a Master. Cassie recoils from Dean’s attempt to comfort her, convinced that her visit led the Masters to Laurel.

Cassie finds Celine swimming in the backyard pool, lit by black light for crime-scene training. Celine recounts Thatcher’s confrontation, his admission that he’s her father, and his remarks about her “bad blood.” She says she always knew the truth because she sees and remembers the underlying bone structure of faces. Recognizing Celine’s talent for eidetic facial memory, Cassie asks for a favor.