Curtis (Gale Gordon) comes back from a Hawaiian vacation with the intention of moving in with his son, Ted, and his family. He arrives just in time to learn that his son's mother-in-law, Lucy (Lucille Ball), Curtis's new business partner, has moved in with the family. Crotchety Curtis is annoyed that not only does he have to put up with her shenanigans at work, but now at home as well.
John Ritter is doing a play in town, and stops into the hardware store for some antique doorhandles. But instead of being helpful, Lucy is hurtful -- she advertantly injures his hands and foot. So Lucy insists that John stay with her. After the lead actress drops out of the play, Lucy talks John into offering her the part of his love interest.
While trying to pass off a Kevin's teddy bear as her own during a clean-up sale, to help avoid taunting from one of Kevin's friends, she sticks it in a bag. The bag is then purchased with the bear inside, so Lucy puts up reward posters around town. When the woman comes in to pick up the reward, she's asking for a lot more than the $50 that Lucy is offering.
Ted and Margo feel that Curtis and Lucy are spoiling their grandchildren too much. It doesn't help matters when Curtis begins building Kevin a treehouse, which begins a quarrel between the couple. While working on the treehouse, Lucy and Curtis decide to relieve Ted and Margo's burden by arguing over which will move out -- and Kevin walks off with the ladder, trapping them in the tree.
Lucy, jealous that everyone else in the family has a trophy to boast, is urged by Becky to join a talent show. After trying her hand at singing, dancing, telling jokes, and doing magic, Lucy finally settles on reciting a song. When she fails to win the trophy, the grandkids get her one of her own that reads ""World's Greatest Grandma.""
An Entertainment Tonight interview gushes about Ball's return, and on-camera she is relaxed and confident.
From the I Love Lucy 35th Anniversary Marathon celebrating Lucy's birthday, I Love Lucy's 35th Anniversary and Life With Lucy. Wishes from Lucie Arnaz, Carol Burnett, Betty White, Whoopie Goldberg, Bea Arthur, Desi Arnaz Jr., Vicki Lawrence, John Ritter, Tom Snyder, Don Rickles, & Mel Torme.