Pobby and Dingan live in Lightning Ridge, New South Wales, the opal capital of Australia. They are friends with Kellyanne Williamson, the daughter of a miner: indeed only she can see them. Pobby and Dingan are imaginary.
Ashmol Williamson, Kellyanne's brother thinks his sister should grow up and stop being such a fruit loop - until the day when Pobby and Dingan disappear. As Kellyanne, grief-stricken, begins to fade away, Ashmol recruits the whole town in the search for Pobby and Dingan. In the end, however, he discovers that only he can find them, and he can only find them if he too begins to believe they are real.