In a flashback to the morning of the day Rosie was killed, at the Larsen house, Tommy and Denny horse around with Rosie while Mitch packs for a family camping trip. Mitch tells Rosie, who is staying behind, to go to Sterling's house after the dance. Wearing her pink backpack, Rosie pauses in the garage for a moment to watch Stan talking on the phone, then walks out the door.
Linden and Holder search for Jamie at Richmond's election rally. Gwen tells them he's half an hour late, as is Richmond. Holder calls in a search for Jamie's campaign car.
At his house, Jamie finds his grandfather, Ted Wright, talking to Richmond. As Jamie wheels Richmond away, Ted says to Jamie, "You think I didn't figure out where you really were that night? The night that girl got herself killed?"
In a parking garage, Gwen tells Holder and Linden that Richmond's driver dropped Richmond off at Jamie's house.
Jamie brings Richmond back to City Hall and triumphantly reports that Mayor Adams is conceding. Prompted by Richmond, Jamie admits he arranged to plant the Indian bones at the waterfront construction site to hurt Adams' campaign, with assistance from Chief Jackson and Michael Ames. In exchange, he promised that Richmond would approve the construction of a casino on the site. When Richmond asks what happened to Rosie, Jamie blurts out, "It was an accident."
In a flashback to the night Rosie was killed, on the Wapi Casino's 10th floor, Jamie, Ames and Chief Jackson confer about the Indian bones. After Ames and Jackson leave, Jamie hears a noise and discovers Rosie, who insists she didn't hear anything. Rosie tries to run away, but Jamie knocks her to the ground.
Jamie tells Richmond that he panicked: "She was going to ruin everything." Richmond points out that Rosie was alive when the car sank into the lake.
In a flashback, Jamie chases Rosie through the woods and bludgeons her with his flashlight.
A dispatcher tells Holder that Jamie's campaign vehicle was found at City Hall.
"I was only thinking of you," Jamie insists, brandishing a gun and scorning Richmond's idealism. "If you want to be a leader, you have to be willing to get blood on your hands." Linden, Holder and Gwen burst into the room. Jamie points his gun at Linden, and Holder shoots Jamie dead. Later, a cop tells Linden that Jamie's gun wasn't loaded.
Stan wakes to find Mitch clearing out Rosie's room. He helps her pack Rosie's belongings into boxes.
At the police station, Ames and Chief Jackson sit in separate interrogation rooms. Holder shows Linden items that were found in Jamie's house, including the missing film from Rosie's Super 8 camera. Lt. Carlson commends Linden and Holder but says there isn't enough evidence to link Ames to the murder.
The Larsens visit their new house. When Stan asks Mitch if she's sure she wants to move, she says yes.
Richmond writes a press release in his office, despite Gwen's insistence that he rest. "The press will have a field day with this," he says. "I don't want Jamie defining my legacy."
Mayor Adams runs into Richmond in the City Council chambers and offers his condolences about Jamie. "You've got the makings of a great leader, Darren," he says.
As Stan packs in the garage, he gazes at Belko's name on a locker. Terry shows up to help Mitch pack, and Mitch says she regrets that she didn't pay attention to Rosie. "You did, Mitch. You always did," reassures Terry.
Gwen calls Richmond, who is at the cemetery visiting his wife Lily's grave. "I think it's time to move on. I'll be in soon," he says.
Linden and Holder revisit the lake in Discovery Park where Rosie's body was found. "No one said what happened to her here," Linden notes. Holder suggests they go talk to the Larsens.
Linden and Holder find Terry in the Larsen garage and tell her they found Rosie's killer. After Terry goes upstairs, Linden notices the tail light on Terry's car is broken and recalls Jasper describing the car that dropped his father off on the night of Rosie's murder as having a broken tail light.
In Rosie's room, Linden and Holder confront Terry about being at the lake when Rosie died. As Stan and Mitch enter the room, Terry apologizes: "Don't be mad at me."
In a flashback, at Discovery Park, Jamie yells at Ames, who was driven to the lake by Terry. "I'm not going to be a part of this. The deal is off," Ames says, insisting that he won't leave his wife to start a new company. Terry quietly gets into the campaign car, shifts the car into drive, and steps back out. The car rolls into the lake and slowly submerges as Rosie screams.
Terry tearfully insists she didn't know it was Rosie in the trunk. Holder restrains Stan as he lunges at Terry. Linden arrests Terry.
At the station, Holder tells Linden that Terry declined a lawyer. Holder gives Linden her badge, which Lt. Carlson reinstated, and a colleague returns Rosie's film from the lab. Linden watches the film on a projector.
Gwen arrives at City Hall, where Richmond is preparing for a meeting. Ames and Chief Jackson arrive and shake hands with Richmond, and Jackson thanks Richmond for his help with the "ridiculous" charges. Richmond closes the door on Gwen.
The Larsen boys wake Stan and Mitch after finding a video on the doorstep. Together they watch Rosie's film, called "What I Know," in which she expresses her love for her family.
As Linden and Holder sit in a car outside the Larsen garage, Holder receives a radio call that a dead body has been found near the airport. Linden gets out of the car. "We got the bad guy," Holder tells her. "Yeah? Who's that?" she answers. Holder drives off, leaving Linden behind. She stares at the Larsen garage for a moment, then walks away.