While twin sisters Tia Mowry and Tamera Mowry gained fame playing twin sisters on the sitcom Sister Sister, this comic fantasy finds them stretching their talents by playing grandmother and granddaughter. When the Donovan family moves from California to Connecticut, 17-year-old Sydney (Tia Mowry) finds it's not easy being in a new town away from her old friends, but her 12-year-old genius brother Willie (Tahj Mowry) is happy as long as he can tinker in his lab with his increasingly complex experiments. Willie is convinced he can defeat the aging process, and while devising an experimental anti-aging formula, he accidentally spills some on a bar of soap. When his grandmother Cat (Hope Clarke) mistakenly uses the tainted soap, she's transformed into a 17-year-old (Tamera Mowry). Her husband Gene (Robert Hooks) follows suit, and is also returned to his teenaged self (Mark Taylor). Cat and Gene are having a fine time reliving their youth and enjoying the thrill of teenage romance, but there's a fly in the ointment Willie learns his formula could have deadly side effects, and now he must discover an antidote to return his grandparents to their older but healthy bodies. Seventeen Again also features an appearance by popular vocal group Boyz II Men; one of the group's singers, Shawn Stockman, served as executive producer for the project.