Walt has caught a cold, which makes Garp endlessly paranoid. He hardly sleeps anymore—whenever he does, he just has bad dreams. In one recurring dream, he's distracted by a "pornographic magazine" (13.6) while his family is bombed from unseen aircrafts.
Meanwhile, Helen finally gives in to Michael's advances. She tries to control the situation, though, demanding that he buy a car for their encounters and that they can only get together at his apartment. She puts her head in his lap during these cross-town rendezvous.
Things start to go bad quickly, though, when a former girlfriend of Michael's named Margie Tallworth drops out of Helen's class "without so much as a note of explanation" (13.51). Uh oh…
Margie has been trailing them and knows pretty much everything. After seeing Duncan and Walt outside Helen's home, she decides to leave a note revealing the affair in Garp's mailbox.
Garp is jogging at the time, and he gets home just as Margie takes the letter out. Margie tries to run away, but drops the note, so Garp reads it and is furious.
He takes Walt and Duncan to soccer practice in a daze. When they return home, Garp takes a bath with Walt. Uncharacteristically, Garp has completely forgotten about dinner.
Helen can tell something is up when she gets home. She calls Garp, but he hides underwater "because he felt such hatred for her" (13.168).
Walt shouts to her that Garp is holding his breath. Garp emerges a few moments later, but he tells Walt to keep the lie going.
Helen panics and runs upstairs only to find Walt and Garp in towels. Helen apologizes, knowing that Garp has learned of the affair, but Garp is cold.
He starts to cry when he realizes that the kids have been watching them fight. He demands that she "tell him goodbye" (13.126) (by him, Garp means her boy toy) without seeing him again—while she does, Garp will go to the movies with Walt and Duncan.
The kids act up the whole way to the movie, but Garp has no patience for their nonsense, and when Walt points out the missing gear-shifter, Garp says that it's their "mother's job" (13.275).
Helen calls Michael, and he comes over, mustache-free. This—along with his pathetic and borderline creepy demeanor—zaps away any attraction she had for him.
Eventually, she promises to sit in the car with him. He starts to cry and Helen, desperate to get this over with, puts her head in his lap.
But then things get dark. Michael forces Helen to perform oral sex on him in the car, and Helen, although horrified, wants to "avoid any scene, at any cost" (13.344), and doesn't fight back.
Garp, meanwhile, has no patience for the movie. He can't get his mind of Helen—he even tries to call the house, but no one picks up. With that, he piles the kids in the car and speeds back home halfway through the film.
He does his usual shut-off-and-coast ritual as he pulls into the dark driveway. As they hit the driveway going "about forty miles per hour" (13.389), Walt says he feels like he's in "a dream" (13.394).