Marion encourages K. C. to date, so she accepts an invitation to Arnold's Gala Costume Ball from Melvin Belvin.

Jenny dumps a nice guy to be with a former Olympic swimmer, but K. C. learns that the swimmer doesn't feel the same way about Jenny as she feels about him. Meanwhile, Fonzie wants to have a swimming pool put in the Cunninghams' backyard.

In an attempt to help Fonzie move on after his break-up with Ashley, Potsie, Chachi, and Roger take him on a retreat to a singles resort. However, to get him to go, they tell him they're going to a sporting camp. When they arrive at the lake, Fonzie discovers what the resort is all about and says he's going to leave. He ends up staying which puts a damper on the rest of the guys' fun.

After realizing they're dating people that look like each other, Joanie and Chachi decide to meet in order to explore the option of getting back together.

Meanwhile, Fonzie wants to adopt an orphaned boy to whom he's been a Big Brother.