Contents • • • • • • • • • • Plot [ ] In 1989, 17-year-old Mike O'Donnell () learns during the start of his high school championship basketball game his girlfriend Scarlet Porter () is pregnant. Moments after the game begins, he leaves the game and goes after Scarlet, abandoning his hopes of going to college and becoming a professional basketball player. Nearly two decades later, Mike (), now 37 years old, finds his life stalled. Scarlet (), now his wife and mother of their two children, has separated from him, forcing him to move in with his geeky, yet extremely wealthy, best friend, Ned Gold (). He has quit his job after he is passed over for a promotion he deserves in favour of a younger female co-worker for simply for being too old, and his high school-age children, 17-year-old Maggie () and 16-year-old Alex () want nothing to do with him.
Later, while visiting his high school to reminisce, an encounter with a mysterious janitor () transforms Mike back into his 17-year-old self. After convincing Ned of his identity, Ned believes that Mike's transformation was caused by a mystical spirit guide who is trying to steer him on a better path. Mike enrolls in high school posing as Mark Gold, Ned's son, and plans to go to college on a basketball. As he befriends his bullied son and discovers that his daughter has a boyfriend, Stan (), who does not respect her and frequently torments Alex, Mike comes to believe that his mission is to help them. Through their children, Mike spends time with Scarlet, who notes his remarkable resemblance to her husband, but rationalizes it as an odd coincidence. Deciding to also try and fix his relationship with Scarlet, Mike begins to finish (under the pretense of getting 'volunteer credit') all of the garden projects he abandoned as an adult. He does his best to separate Stan and Maggie while also encouraging Alex to be more confident so he can make the basketball team and go out with a girl he has a crush on named Nicole.