Howard Amis, a top political campaign manager, is worried that his wife Lisa, who is a California State Assemblywoman, is missing. Desperate to find her, he called in a favor to the mayor of Los Angeles, who put Crews and Seever on the job. Upon his return from a last-minute business trip, Howard became concerned when he saw his wife's car at home and learned she wasn't in her office. Seever, who has mayoral aspirations, is thrilled to be in the presence of the political powerhouse. Howard says her friends haven't seen her; her phone goes to voicemail and when asked, he dismisses the possibility of an affair.
Crews notices cat food asks where the cat is. Howard hasn't seen Luther, who he says is his wife's cat, but wasn't looking for him. Crews looks outside and sees Luther sitting on the cover of their hot tub. In the back yard, Crews asks Howard to call his wife's phone. When he does, it rings and they find it by the tub next to a towel and her flip flops. When they unlatch the cover and remove it, they discover Lisa inside, dead of four gunshot wounds to the chest. Howard stands there stunned.
Crews and Seever speculate that the killer, cloaked by the sound of the water jets, easily snuck up on Lisa and masked the sound of the gun by firing it under water. Then, he escaped over the fence. When they ask Howard if anyone would want to kill his wife, he thinks and then says, "Yes. Initiative 38." At Lisa's office, they learn from her assistant Ella Holden that Lisa was spearheading an initiative that would ban handguns. Ella, seeing an opportunity, wants to release a list of suspects, namely P&K Firearms, to help the initiative. Crews says no.
While talking to them, Ella picks Crews out as mayoral material, saying she could make him mayor in three weeks. The slight angers Seever. Crews calls Reese but only gets voicemail. When he gets in the car, he sees Seever is angry at being overlooked. Crews teases her for being a sore loser, which she denies, but does admit to growing up under the shadow of four older brothers.
Crews, Seever and Tidwell discuss that Lisa was gearing up to run for U.S. Senate while Howard ran campaigns for anyone on the other side of the political aisle from her. Tidwell says ballistics revealed two different guns were used, meaning there were two shooters. Tidwell's bets are on Howard. He notices Seever's usually sunny demeanor is missing, but she denies acting differently. Crews asks Tidwell if he's heard from Reese. Tidwell says he's gotten voicemail on her cell for the last few days, and becomes concerned at why Crews is asking. He's especially unnerved when Crews asks him to GPS Reese's cell phone.
Crews and Seever respond to a shots fired call at P&K Firearms. In the lobby, the entire staff is packing heat, which Seever points out is well within their rights inside the building. Stark says that Ella ran past security and made a dash for P&K CEO Whitney Paxman's office to give her a body bag in protest of Lisa's murder. Paxman fired a warning shot to stop her. Seever, still miffed at Ella, displays no shortage of satisfaction when she instructs the cops to arrest Ella and give Paxman her gun back. "Well within her rights," Seever says.
At the station, Tidwell uses a random case number to order the GPS track on Reese's cell phone. Meanwhile, Crews and Seever talk to Whitney at her office. Whitney, who's confident that Initiative 38 will never pass, initially wanted to hire Lisa but she chose the "other side." During their meeting, an employee turns on the TV, where Ella is publicly naming P&K Firearms as a suspect in Lisa's murder. Crews and Seever wonder why someone would send two shooters to kill an unarmed woman, then realize that they didn't. Howard, who went out of town last minute, was the intended second target.
At Howard's home, Crews and Seever hear him pleading for help from inside. They enter, guns drawn, to see Howard holding a flower box. Inside: a homemade bomb with a counter-balance timer. Howard picked it up on his doorstep, thinking it was flowers for Lisa. Upon opening it, he activated the timer. A note inside reads, "Who is the little one now?" When Crews asks, Howard says he quit his business because he didn't really believe in what he was doing like Lisa had. Seeing Howard is losing his battle of nerves, Seever takes the bomb from him and holds it steady until the bomb squad arrives.
After the bomb squad diffuses the bomb, Howard says he has no idea what the note means or who could have written it. A visit to Ella reveals that Lisa referred to her younger sister Jackie as "the little one." Back at Howard's home, he says he had totally forgotten about that, but confirms it. Lisa, who always took care of her little sister, was nicked named "the big one." However, Lisa stopped talking to her a year ago. Ella says that Jackie was trouble, into drugs and bad men. After getting her address, which Ella refers to as "way the hell out there," they pay Jackie a visit.
When Crews and Seever arrive at Jackie's cabin, they see a forest ranger's truck. As soon as they get out of their car they come under fire from Jackie, who's taken cover in the woods. They shout back and forth at each other, and Jackie says that someone on her radio said the people who killed Lisa are coming for her. Once Crews convinces her that's not the case, she surrenders.
Tidwell tells Crews the GPS came back negative. He wants to know what's going on. Crews says he just wants to know why she's not answering her phone. Tidwell says if the battery is still in her phone they can track it, but LAPD doesn't have the needed equipment. They go to the FBI, where Agent Ray says Reese is on assignment and unreachable. When Tidwell demands to talk to Reese, Ray smugly asks if his interest in Reese is personal or professional. Enraged, Tidwell shoves the contents off her desk. The boys draw their guns, but Ray calms things down and says she'll tell Reese they were here.
In the interrogation room, Jackie sticks by her story about the radio warning. Confronted with an old record from police stop, Jackie says she was at a bus stop talking to some guy when a cop picked her up for solicitation. Lisa helped her out of the bind but didn't believe Jackie was innocent. Jackie says even when she used drugs, she never sold herself. Even so, an angered Lisa called Jackie's boyfriend to say she was a whore. When Jackie says they use explosives at the park, Seever asks if she wants a lawyer. "Lisa usually did that for me," Jackie says, at a loss.
Ted visits Amanda Puryer and says Crews wants to hire her. At first, she's dubious, but when Ted flatters her for having superior equipment, she's in. Crews and Seever talk to the cop who arrested Jackie. He says he was responding to an anonymous tip and confirms that he cut her loose because of Lisa. He adds that Jackie didn't seem like a hooker. Crews and Seever, on a visit to P&K Firearms, put together that Howard ran a campaign on them by orchestrating all the events so he'd look like a victim. Their suspicions are further confirmed when Howard announces that he's running for U.S. Senate.
Crews, Seever and Tidwell watch Howard on TV, where he says that Lisa's murder taught him to stand up for what he believed in. Inspired by her, he announces his candidacy for U.S. Senate. In her memory, he's fully supporting Initiative 38. To demonstrate his point, he pours a bucket of guns in a kiln, including most notably, a 9mm and a .22, which were used to kill Lisa. They realize there may have been two guns, but there was only one shooter.
At Amanda's office, they wait to see if Reese's phone can be traced. Amanda surprises Ted by telling him where Olivia is. She says that Olivia is in Italy alone, and called him twice but hung up both times. Ted asks how she knew he wanted to know. "I know everything," Amanda says. They get a hit on Reese's phone, which is 15 miles away. Amanda gets her gun and is ready to go, but when Ted asks if they should call Charlie first, she asks where his sense of adventure is. She then says she has a spare gun, and asks if Ted wants to borrow it.
At Lisa's office, Ella is shocked when Crews and Seever suspect Howard killed Lisa to run for the Senate. Since the time of Lisa's death can't be determined due to the water temperature, being in Las Vegas doesn't clear him of the murder. Ella admits tearing the sisters apart, at Howard's direction. She tipped off the police, pretended she was Lisa when they called, and called Jackie's boyfriend. She says they did it because they were afraid of Jackie hurting Lisa's chances to be Senator. Crews tells Ella to bring Howard a tape; it's a recording of Lisa saying she fears Howard wants to kill her.
At Howard's campaign rally, Ella pulls a switch on the detectives. It turns out she's Howard's campaign manager and tells Howard about their ruse to "get him." Over the P.A. system, she broadcasts her recording of Crews instructing her to lie. Howard slams the corruption in the LAPD, which Lisa campaigned against. He swears to stop this kind of abuse "in her name." Crews tells Ella to play the other tape. She does, and Lisa's voice is broadcast saying she's afraid of Howard and if anything happens to her, he killed her. As the stunned campaign workers listen, Howard cracks and outs Ella for knowing everything.
As Howard and Ella are being led away in handcuffs, Howard sees Jackie and realizes it was her voice on the tape. Stunned, he says, "It was you." Jackie, feeling the satisfaction of justice served in more than one way, tells him everyone always said she sounded just like Lisa.
Ted and Amanda go to an abandoned trailer park and find two sets of tire tracks in the dirt as well as evidence of someone being dragged from one car to the other. From the scuff marks, she was alive when they did it. Amanda follows the signal and finds Reese's phone and gun, discarded. They both agree that it's now time to call Charlie. When Crews learns what they found, he realizes he needs to talk to Roman Nevikov.
Crews and Ted go to the maximum security prison where Roman is being held, but the person who approaches the glass isn't Roman. Another prisoner, who's enjoying being a part of getting one over on the police, imitates a fake Russian accent and says he's Roman Nevikov. At the look on Crews's face, he cracks up. It's there that Crews realizes Roman is on the loose, having paid this guy to do his time. With masked fury, he quietly tells Ted that he needs a bigger gun.