A shadowy figure breaks into the Hall of Justice. Slipping by the guard and the custodian, the figure goes to the courtroom and replaces the judge's gavel with a special one of his own. The next day, Judge Maxwell calls the courtroom to order, strikes the gavel, and an explosion kills the judge and demolishes the courtroom.
Frank goes to headquarters to get a report on the bombing. Ed informs him that Maxwell was known for his harsh sentences, and they've checked the record of recently-released criminals he tried. They check out Eddie Casales, a bomb expert, at his last known address. They meet Eddie's ex-wife Lana, who insisted on a divorce from Eddie while he was in prison. Now Lana works with charities. She tells them about her misfortune and informs them that Eddie is now seeing a floozy named Mimi De Jour at the Club Flamingo.
Frank and Ed go to talk to Mimi. She's worried he's in trouble but insists that he was with her at the movies the night before Maxwell's death. Eddie arrives and figures that the police are trying to frame him for the murder. Once the police leave, Eddie tells Mimi that she did the right thing by lying about where he was.
Next, Frank checks in with police scientist Ted Olson. Ted has determined that the book was made by an amateur, not a professional. He also recommends that the irritable Frank switch to decaf, a suggestion that Frank cheerfully accepts.
That night, the bomber goes to a parked car and puts explosives in the engine. The next morning, a man comes out, starts the car, and is blown up. Police Squad is called in and they determine the dead man was John Simmongton, a former district attorney who helped send Eddie to prison. They also find a book of Club Flamingo matches on the scene, seemingly confirming Eddie's guilt. They interrogate Eddie, who can't remember what movie he went to with Mimi. Over Frank's objections, Ed releases Eddie to the lack of non-circumstantial evidence.
Mimi calls Frank and sets up a meeting at the Club Flamingo. She admits she lied about Eddie's alibi but he didn't tell her where he was that night. She also mentions that Eddie dumped Lana. Frank decides to check in with Johnny the Snitch, who reveals that Eddie is a Brewers fan with season tickets. Next, Frank calls Lana and warns her that they had to release Eddie. He informs her that Mimi ha accepted police protection and the same offer is open to Lana. Lana, seemingly unconcerned, says she doesn't need it and that she's leaving town.
Frank and Ed watch Mimi's apartment that night. The mystery bomber plants explosives outside the apartment building and then moves down the street to detonate them. Frank and Ed spot him and move in, and discover that the bomber is… Lana. Lana warns them to back off or she'll blow up the entire building. When they refuse, she triggers the dynamite, but nothing happens. Eddie comes over, revealing that he disarmed the dynamite and saved the day. The police take Lana into custody. She's sent to Statesville Prison, and Frank figures that Eddie lied about his alibi because he went over the state line to catch a Brewers game. They decide to give Eddie a break: no man should be deprived of baseball.