While looking for evidence against a man who shot his cheating wife's boyfriend, police divers find a decades-old van in the Hudson River. Inside the van is the skeleton of someone who was clearly murdered. The victim is identified as David Bernstein, a student activist. He disappeared in 1968, the day after he'd been arrested at a protest against the Vietnam War. The evidence suggests the killer is Darryl Grady, a security guard at David's university; who hated the protestors because his son was killed in Vietnam. Grady is now elderly and [[ObfuscatingInsanity seemingly]] senile.

Carmichael discovers that David was an undercover cop tasked with infiltrating student groups and provoking them into criminal acts. When the police refuse to release David's file, she interviews his old co-workers. One of them says that his field handler, Ross Macmillan, saw Grady driving David's van after the protest. [=McCoy=] wants to use this as leverage to get David's file and find out what the police were really doing. But Carmichael, who sees the student activists as terrorists, is disgusted by his actions.

[=McCoy=] deliberately wrecks any attempt at a plea and requests to subpoena David's police file. He convinces the judge to hold a hearing with Macmillan - who confirms he saw Grady driving the van. Macmillan told his superiors about it, but they didn't care, since David was becoming uncomfortable with the job. They ordered Macmillan to pin David's disappearance on the Black Panthers to ensure he'd stay quiet if he ever returned. The judge agrees with [=McCoy=] that the police's actions were illegal. She allows the subpoena.

David's file shows that he'd repeatedly provoked Grady in the weeks leading up to the murder. Grady accepts a lenient plea for manslaughter. He confesses he lost control because he was so enraged by seeing David desecrate a war memorial - which was all part of David's orders. [=McCoy=] still blames the police for David's death, although Carmichael disagrees.

!! Tropes in this episode
* ADeadlyAffair: The episode starts with a man who shoots his cheating wife's boyfriend, which is a failed attempt at this.
* DirtyCop: Pretty much everyone in David's division qualifies as this. Their job was to provoke anyone considered too "radical" into criminal acts, and if that didn't work, make them look like criminals.
* OutlivingOnesOffspring: David's mother was still alive after his death.
* RevisitingTheColdCase: The case of David's disappearance was closed with no results. It gets reopened after his body is found in the Hudson.
* ShiksaGoddess: David Bernstein was Jewish but preferred Gentile girlfriends.
* ShoutOut: a tape of Music/SgtPeppersLonelyHeartsClubBand is found within the van. Curtis calls it "''Dr.'' Pepper's", though.