Basket Case is the story of Jack Tagger, a former investigative journalist who has been demoted to obituary writer. Tagger becomes obsessed with the death of a has-been rock star, Jimmy Stoma, and begins investigating his possible murder in hopes of getting his old job back. Other members of Stoma's band are killed, and Tagger suspects Cleo Rio, Stoma's former girlfriend.
Tagger finds and decrypts a computer drive containing Stoma's new, unreleased album, and a theory develops that Rio had Stoma killed in order to steal one of the songs. Rio has Tagger's girlfriend kidnapped, demanding the recording as ransom. A climactic meeting of several main characters results in the accidental death of Rio's bodyguard and boyfriend.
Stoma's body is exhumed, and Rio's complicity in his death is confirmed. She is arrested and convicted for the murder. The posthumously released album becomes a hit, and Tagger is restored to his old position of investigative reporter.