A group of homeless men are found beaten to death under a railway bridge. The autopsy shows that all the victims had the number 377 carved into their bodies—the hallmark of the "Boxcar Basher", an unknown serial killer who targets homeless men. But on a closer look at the "Boxcar Basher" killings, Lupo and Bernard conclude that these murders are the work of a copycat. It's possible that one victim, Paco, was mistaken for the "Bipolar Roller": an eccentric skater who has schizophrenia. His real name is Jonah Applebaum and he earns good money from his image being used on a clothing line, although he chooses to sleep rough. The detectives think that the money might be a motive to kill Jonah. But a knife used to carve the victims is found among Jonah's possessions, so he is charged with all three murders.
Cutter and Rubirosa investigate the possibility that Jonah's business partners Grant and Bob Carpenter could be responsible. Unknown to him, they'd been trying to shut down the clothing line, and they may have believed Paco was Jonah. The Carpenters are arrested when it's discovered that they have been Googling the Boxcar Basher, and the GPS on their phones places them near the scene of the murder at the time. Jonah gets out on bail - but then forensic evidence proves he's the Boxcar Basher. With McCoy's chances of re-election hanging in the balance over the mistake, Jonah is arrested again.
Cutter and Rubirosa charge the Carpenters with the three murders under the bridge, and Jonah with the murders of the Basher's previous victims. Olivet examines Jonah and reports that he killed because he believed his victims were Russian spies. Because of Jonah's schizophrenia, he has a paranoid delusion that the KGB is out to kill him; he believed the clothing business was a cover for a government operation, and that the Carpenters were his handlers. Now Cutter and Rubirosa need Jonah to testify against the Carpenters, but he refuses to take antipsychotic medication. The defence exploits his condition when he's put on the stand.
Cutter convinces Jonah that all the DAs are Russian agents. Jonah flies into a rage and violently attacks Cutter; legally, as a danger to himself and others, there are grounds for him to be forcibly given medication. Jonah, now stable, testifies that he committed the Boxcar Basher murders but did not kill the men under the bridge. After he told the Carpenters that he'd killed several people, he overheard them say that they needed to find a way out of the business, and later saw them take the knife. The Carpenters request a deal. Rubirosa and Cutter later tell McCoy that although Jonah's medication makes him too tired to skate, his condition is improving.
This episode contains examples of:
- Career-Ending Injury: Jonah was a record-breaking pole vaulter in college. He broke his arm during a car accident and that ended his athletic career. He believed that Russian spies were responsible.
- Frame-Up: This was the Carpenters' intention after they discovered they hadn't really killed Jonah.
- Gratuitous Russian: To provoke Jonah, Cutter tells him that all the DAs are indeed Russian agents. To reinforce the deception, he whispers "ты глупый американски дрюки"translation in Jonah's ear.
- Insane Equals Violent: Jonah is schizophrenic and committed nine murders as the "Boxcar Basher."
- My God, What Have I Done?: Jonah has such a moment on the stand and says he wishes the Carpenters had killed him.
- No Medication for Me: Jonah refuses to take his anti-psychotic meds on account that it makes him tired. Cutter deliberately provokes him so that he is forced to take him.
- The Paranoiac: Jonah is this because of his schizophrenia.
