Television show host Brett and his laid-back science journalist girlfriend Tash despair that they will ever truly understand each other. On their first anniversary, under a full moon, a frustrated Tash declares her wish that they could swap lives. The next morning, Brett and Tash awaken to find Tash's wish has come true. Forced to confront the unfamiliar sensations of their "new" bodies, both must navigate strange new experiences with friends and co-workers.