In an attempt to move on from their parents' recent tragic deaths, Evie encourages her brothers, Ian and Greg, to go on a fishing trip in their beloved FJ Holden ute. But Evie's world is once more turned upside down when Ian returns from the fishing trip, not with Greg (or even some fish), but with a beautiful woman named Salamanda and a white pony named Trevor.

Ian insists that Trevor is not merely a pony but a unicorn who chose him and Greg to become the King's Champions and embark on an adventure in the enchanted Stonewynne Valley. To make matters worse, Ian informs Evie that Greg chose to remain in the enchanted valley instead of returning home to their farm. And don't get Evie started on Salamanda's fantastical backstory...

Determined to be reunited with Greg, Evie and Ian embark on a quest with Salamanda to discover a new type of magic that they can use to open a new portal to the Stonewynne Valley. An adventure that leads them from their farm in the Hunter Valley to Sydney's Brookvale Oval, the 1999 State of Origin, and Cathy Freeman's legendary race at the Sydney 2000 Olympic Games.

Set in Australia at the end of the 20th century, My Brother's Unicorn is a heartwarming and captivating fantasy about loss and grief, love and family, forgiveness and redemption, and rugby league, the greatest game of all.