Hallie Parker and Annie James are identical twins who were separated at a young age due to their parents' divorce. Unbeknownst to their parents, the girls are sent to the same summer camp, where they meet, discover the truth about their relationship, and come up with a plan to switch places in an effort to reunite their mother and father.

When ex-con artist Harry claims that a secret treasure is hidden inside Candleshoe, an English estate, he creates an elaborate plan to find and steal the prize. By convincing a girl named Casey to impersonate the estate owner's long-lost granddaughter, Harry hopes to uncover the treasure's location. But when Casey has a change of heart, she must follow the clues and find the treasure, in order to save Candleshoe and stop Harry before it is too late.