Maggie returns to work. She confides to OA that she could have chosen to stay home longer. A man and a runner on a park bench are shot and killed: Marisol Lugo, a law student on track to attend the FBI Academy, and Kiko Cortez, a young man with possible gang ties. The murder weapon had been used on three previous gang shootings. Kiko's girlfriend Brianna says Kiko had been selling drugs and crossed that gang. OA discovers Maggie has a new prescription for anti-anxiety drugs, which she insists she hasn't taken. Maggie and OA arrest Mateo Diaz, who previously had beat up Kiko. Mateo denies shooting Kiko. Sam, a rave organizer, is Mateo's secret boyfriend and they've been dealing at Sam's club. They were together that night. Mateo fingers the gang boss, Jose. OA is opposed to Maggie going undercover as a club owner to entrap Jose's lieutenant Frankie. The meeting goes sideways when Frankie gets antsy and he pulls a gun on Maggie. He and Mateo wrestle for the gun, which goes off, shooting Frankie. Maggie keeps flashing back to when she got poisoned. Maggie and OA back each other in a debrief with Isobel. Jose demands a meeting with Mateo, so Isobel insists he wears a wire and get Jose to incriminate himself. Jose wants Maggie brought to the meeting. Maggie agrees. An anxious OA insists on moving closer to the meet. Maggie tells Jose she accidentally shot Frankie. Jose wants Mateo to shoot Maggie. Maggie gives the signal "Payback" and the team moves in. Maggie tracks Jose and she and OA follow him down a tunnel. He tries to drive out but gets boxed in. Jose had the murder weapon still on him. Maggie gets Mateo and Sam into witness protection. Maggie and OA argue about trust.