Best friends Minty and Billie become aware that something strange is happening in their town. Who are the two suspicious people heading down the forbidden path that leads to the abandoned house at the back of the school? What are they carrying and why is it rolled up in carpet? When the girls investigate, they stumble upon an ancient mystery involving a lost treasure. Suddenly they're caught in a web of cryptic clues, spirits, a family curse and something much bigger than they could have imagined.

With the news that Billie may have to change schools if she doesn't win a scholarship the treasure becomes their best hope of saving their friendship- but only if they find it first. To do so they must break almost every school rule, outsmart a watchful headmistress, a scary teacher in charge of discipline, and a pesky new girl who threatens to derail their plans.

Minty must dig deep to find her courage, Billie wants to make her mum proud and both girls come to understand that exam marks are not the only measure of success.