Wallace is in some trouble of his own after being caught cheating on his Mechanical Engineering test. Dean O'Dell decides to go easy on Wallace because he is an athlete. Wallace agrees to take a zero on the exam and is offered an opportunity to drop out of the class after the drop date. Wallace mulls over his options and decides to keep the class because Mechanical Engineering is what he wants to do with his life. Balancing basketball and class proves to be difficult for Wallace and he has to make a choice between the two. He chooses to sit out basketball, where he had a chance to be a starter, and concentrate on his studies.Piz tries to get Veronica to come to go bowling with him and 'the gang.' Unbeknownst to her, 'the gang' is just Wallace, who doesn't go because he wants to study. So the evening consists of just Piz, Veronica, Logan, and a dismal Parker. Parker gets onto a winning streak and admits that she's finally having fun, and even that she has an interest in Piz - who, the next day, admits to Veronica that he isn't interested in Parker. Nonetheless, Parker insists on stopping by to see Piz record his radio show, along with Veronica, where the three have a brief encounter with Mercer Hayes, the student who runs the on-campus casino. Parker tells Veronica that she recognizes Mercer's cologne from the night of her rape. Veronica searches Mercer's room and finds an electric razor, hidden in his drawer. Veronica takes the information to Sheriff Lamb, who reveals that the Sheriff's Department recovered the cashbox stolen from Mercer's casino (in President Evil), and that they found empty vials of GHB, the drug used in the rapes.
Keith has been socially seeing Harmony, professing to Veronica that they are only good friends and honestly believing it. But one evening when they're having drinks at the Neptune Grand Hotel, Harmony non-so-subtly asks Keith if he'd like to go up to the room she's already booked. She says that she doesn't want to lie on her deathbed and regret what might have been. Keith replies that he doesn't want to regret doing something stupid and leaves. Driving home, he's involved in a car accident when pickup truck smashes into him in an intersection. Both Keith and the other driver are fine, but Keith, having had a near-death experience, has found a new take on regret, and goes back to Harmony's room where they kiss and tear each others' clothes off.Meanwhile, Veronica follows the trail of clues to a Rory Finch who posted her paper online from the Neptune Grand. Using a contact of Logan's, Veronica finds out Rory Finch's hotel room and goes up to meet him. To her surprise, Dean O'Dell's wife opens the door, wearing a robe. Veronica apologizes and heads back toward the elevator. On the way there, she encounters Professor Landry getting off the elevator. After having a brief conversation with him, she calls out "Rory Finch" - to which he responds.
Veronica heads to her Tim's office and tells him she knows who posted the paper online: Tim did. When she asks him why, Tim explains to her, "hypothetically speaking," that if he did post her paper, he would have done it to lead Veronica to discover the type of person her Professor Landry really is: The type of person that would sleep with the Dean's wife. About to leave, Veronica sees Tim's back wall, which is covered with news articles, pictures, maps, and charts all pertaining to the Hearst rapes. Tim tells Veronica that no forensic evidence of the perpetrators was left at the scenes, and the audience realizes that Tim has been investigating the rapes as well.
In the campus food court, Veronica eats with Dean O'Dell, but refrains from telling him about his wife. Logan interrupts to tell Veronica that Mercer has been arrested by Lamb, but is innocent: He was with Logan during at least one of the rapes doing something that Logan refuses to talk about.
- Claire Nordhouse wasn't raped. The Asian boy in the ATM photo was her boyfriend and she faked her rape.
- No hair or DNA from the rapist has ever been found at the crime scenes.
- Parker recognizes Mercer's cologne as being the same as the rapist's.
- Veronica finds clippers in Mercer's room.
- Wallace chooses to sit out of basketball for the semester to concentrate on his Mechanical Engineering class.
- Sheriff Lamb said that 2 vials of the date rape drug GHB, the same used in at least two of the campus rapes, were found in Mercer's stolen cash box from his illegal casino.
- Veronica discovers Professor Landry is having an affair with the Dean's wife.
- Logan tells Veronica that Mercer couldn't be the rapist because he was with him at the time of one of the rapes.
- "Say About Me" - Tamar Berk
- "Prince of Wands" - Douglas Armour
- "I'm Not in Love" - 10cc
- The episode had an estimated audience of 2.87 million viewers on its initial airing. 
- The title Hi, Infidelity is a reference to the book High Fidelity by British author Nick Hornby, and later a film starring John Cusack. It also refers to the extramarital affairs between Harmony Chase & Keith Mars and Hank Landry & Mindy O'Dell.
- At the bowling alley, there was a sign that read "Wednesday: THE BIG LEBOWLSKI." This is another of many references to the movie, The Big Lebowski in Veronica Mars.