"Presumed Innocent" is about Rusty Sabich, a prosecutor played by Harrison Ford, investigating the murder of a woman with whom he once had an affair. As Sabich digs deeper into the case, he finds that he has been framed for the crime.
"Presumed Innocent" begins with Carolyn Polhemus, played by Greta Scacchi, found raped and murdered in her apartment. Despite his personal connection to the victim, Sabich is instructed to take the case by his superior, Raymond Horgan, played by Brian Dennehy. Sabich hires his friend Dan Lipranzer, played by John Spencer, to assist in the investigation. As Sabich and Lipranzer investigate, they discover evidence that appears to be intended to frame Sabich.
Sabich is put on trial for the murder, prompting him to hire attorney Alejandro Stern, played by Raul Julia. As the trial is going on, Lipranzer uncovers evidence that the judge presiding over the trial took a bribe. The charges against Sabich are dismissed, and Rusty is free, but he still doesn't know who committed the murder.
The end of the film reveals that Sabich's wife, Barbara, played by Bonnie Bedelia, murdered Carolyn as revenge for her affair with Sabich. Though Sabich uncovers the evidence incriminating his wife, he refuses to tell anyone, as he doesn't want their child to grow up without a mother.