Brendan and Nick are identical twins. With their older sister Ami and their mother, they are moving to a small town just six months after the death of their father. While the twins do their best to help, Ami is sullen and stays mostly in her room. The only thing that seems to interest her is unicorns. One day on an outing at a local swimming hole, Ami finds a hoofprint. She is convinced that there is a unicorn in the area. Soon, she draws Brendan and Nick into a game in which they try to catch the mythical creature. But what are they truly chasing?