Nash and Joe are on the shooting range for their qualification tests with their weapons. They visit with Caitlin. As Nash turns to leave, Caitlin's gun discharges, and the bullet ricochets into Nash's butt.
At the hospital, Dr. Berry tells Nash not to move for a week, and that the bullet will be left to heal in his backside. Rick Bettina announces he will run the SIU in Nash's absence. Evan spots Cassidy there, but Cassidy has been too busy with her studies for her relationship with Evan.
Two FBI agents present themselves to Rick as temporary head of SIU. The FBI wants SIU help to catch Frank Corvin, a notorious con man and swindler. Rick is anxious to impress the FBI and agrees to help with half million dollars of bait money. Joe and Rick meet with Corvin in a scam to invest the half million in a chain of restaurants. Rick meets a woman (planted there by Corvin) and mistakenly thinks the woman is attracted to him. Rick gets her phone number.
Cassidy meets a new friend, Cliff, from her history class. Cassidy has been getting mysterious phone calls, and Evan is annoyed that she does not have time for him. Things come to a head at the library - Cassidy and Evan are fuming at each other, with Cliff in between. Later, Cliff is beaten up, and Cliff claims it was Evan that did it. A frightened and angry Cassidy warns Evan to stay away from her.
Joe and Rick meet with Corvin with the cash to close the deal. A man starts choking on his meal; Joe and Rick rush to help. They finish their deal - the suitcase of money is handed over to Corvin and he is promptly arrested by the FBI and taken away. At the SIU, Rick opens the suitcase to discover only phone books inside - Joe realizes the SIU has been conned by phony FBI agents. They all agree not to tell Nash, and try to figure a way to get the money back.
Meanwhile, Caitlin has been suspended for shooting Nash. But Nash examines her gun and discovers a defective spring which caused her gun to unintentionally discharge. Nash helps clear Caitlin - she kisses Nash but they are interrupted by the overly protective Nick.
Cassidy's room mate, Miranda, warns Cassidy about her new friend Cliff. Rumors are that he raped and locked up a girl in a crawlspace. Studying late at night in the library, Cliff attacks Miranda (who works at the library) and stalks Cassidy. Evan arrives just as Cassidy escapes the library. Evan finds Miranda locked up in a cabinet, but Cliff has escaped.
Evan takes Cassidy to Nash's apartment. Inside, Nick has just put Nash to sleep with a sleeping pill. Outside, Evan is attacked by Cliff. Evan staggers into Nash apartment. Cliff follows, subduing Evan. Cassidy, with kitchen knife in hand, defends herself. But just as Cliff is about to stab Cassidy with her own kitchen knife, a sedated, but awakened Nash shoots Cliff dead with 6 shots from his gun.
Joe obtains fingerprints and an ID from the pen the woman used to give Rick her phone number. Through her, they arrange a meeting. Posing as waiter, Harvey and the SIU arrest the two phony FBI men and recover the suitcase of money. Nash returns to the SIU two days early from his convalescence. Caitlin brings flowers to Nash's apartment, but he is not there. With Nick there, Caitlin decides against leaving a personal note with her flowers.
For more, see commentary for Episode 66