The following version of this book was used to create this guide: O’Brien, Tim. Tomcat in Love. Broadway Books, 1998.

Tim O'Brien's novel begins in Minnesota in 1952, where Thomas and Herbie are neighbors and childhood best friends. At seven years old, Thomas is deeply enamored with Herbie’s sister, Lorna Sue. When Thomas starts dating Lorna Sue during their junior year of high school, Herbie shows disdain toward their relationship. Thomas and Lorna Sue eventually marry and are together for 20 years.

Lorna Sue divorces Thomas after Herbie reveals a secret pile of private documents that Thomas has been hiding under his mattress. It contains checks written to a fake psychiatrist, whom Thomas had been promising Lorna Sue that he had been seeing. Since Lorna Sue broke his heart, Thomas decides to take revenge by destroying her relationship with her new husband, who is referred to only as “the tycoon” (23). While stalking the couple in Tampa, he purchases lingerie and a sex toy, intending to plant them the tycoon’s car to make Lorna Sue question the tycoon’s fidelity.

In Minneapolis, Thomas visits the house he grew up in as a child when the owner of the house, Mrs. Kooshof, discovers him. At first she apprehends him as a trespasser, but then, beguiled by his good looks, invites him into her home. Thomas divulges his plans for retribution to Mrs. Kooshof. His goal is to have Lorna Sue to fall back in love with him, remarry her and then leave her so that she may experience the same heartbreak she made him feel. Mrs. Kooshof continues to enter into a physical relationship with Thomas as she is hoping he will fall in love with her instead.

Thomas has always been suspicious of how close Lorna Sue and Herbie are as siblings ever since they were children. At one point during his marriage to Lorna Sue, he even accuses her of incest with her brother. Thomas believes the tycoon would likely be skeptical of Lorna Sue and Herbie’s relationship. Without knowing that Thomas was actually the one that arranged their rendezvous, Lorna Sue and Herbie arrive for dinner, each thinking that the other one had invited them. Suddenly as part of Thomas’s premeditated plan, the tycoon enters and is angry when he sees Lorna Sue and Herbie alone together.

Mrs. Kooshof is exasperated that her attempts to get Thomas to fall in love with her are clearly unsuccessful and she packs her bags to leave him, as she wants no further part in his manipulative schemes. She seeks out Herbie in order to find out the truth about Thomas’s transgressions during his marriage to Lorna Sue. She discovers the reason Lorna Sue wanted him to see a psychiatrist was because Thomas kept an inappropriate ledger under his mattress as well. This ledger contains various tallies and lists of lewd behavior with women under various titles including meaningful gazes, hand holdings, nuzzling, near misses, and spankings. It is clear that Thomas feels his behavior never betrayed his marriage, but the very act of compiling interactions with women into personal statistics was so perverse that it drove Lorna Sue away. In order to maintain relations with Mrs. Kooshof, Thomas begrudgingly asks for her hand in marriage.

Lorna Sue calls Thomas and she says that she forgives him for everything and wants him back. She warns Thomas that Herbie and the tycoon are in town as well. Thomas is a professor of Linguistics at a local university. He attends a class he is about to teach when he sees Herbie and the tycoon in the audience. They force Thomas to strip down to only his underpants to be spanked as a form of cruel public humiliation in front of his entire class. Lorna Sue enters to witness this act of degradation and leaves with her arm around the tycoon.

Thomas is forced to resign from his tenure position when two beautiful young female students reveal that he has written their senior theses for them in exchange for their silence regarding sexual harassment claims toward him.

After the loss of his career and Lorna Sue, Thomas retreats with Mrs. Kooshof to Owago and teaches part time at a daycare center. One of the children suggests that he bears a resemblance to Captain Nineteen, a host of a popular children’s television show who had recently passed away. Thomas tries out for the tv show’s replacement and has a mental breakdown during the audition, crying, calling out for Lorna Sue and even threatens suicide. He stays in a mental hospital for six days. After his release, he stays with Mrs. Kooshof and as he descends into madness he begins to fashion home made bombs. One day, Thomas finds all of his bombs stolen. Thomas goes to Herbie’s house to retrieve the bombs. The two engage in a deep discussion in which they learn that they have both been emotionally manipulated by Lorna Sue for many years. Thomas realizes that it was not Herbie who stole his bombs, but Lorna Sue.

In the middle of one night, Lorna Sue uses multiple bombs on Mrs. Kooshof’s house, where she and Thomas are staying. Herbie calls Thomas to come to his house. Lorna Sue’s family and the tycoon are in hysterics over her actions. Herbie, Thomas and Mrs. Kooshof go up to the attic, where Lorna Sue is hiding with the rest of the bombs. She threatens to blow up the entire house if Thomas does not proclaim his adoration for her. This is when Thomas realizes that while he does love Lorna Sue, he no longer believes her to be sacred. He rejects her while Mrs. Kooshof takes the fuse from Lorna Sue and extinguishes it.

Thomas and Mrs. Kooshof move to an undisclosed tropical location where they now live a peaceful life together. He maintains his newfound friendship with Herbie and Lorna Sue stays married to the tycoon.