Harvie is a smart but a bit too lively boy with one ambition, to finish the last level of his computer game. Once in the Gamers Hall of Fame, his absent-minded father, would finally be proud of him. But finishing the game turns out to be only the start of a real adventure that takes Harvie, his dog Jerry, and his friend Monica deep into the forgotten realms of the city's old puppet museum.

In the world of timid water sprites who do all they can to keep out of sight of all people, a courageous and rather unconventional girl sprite, Pearl. Her dream is to become a secret agent, cross into the human world and find a key there to unlock a magic shell. According to legend, this Shell will save her people. And it’s high time for this! Destruction is fast approaching the last underwater town where the last remaining water sprites in the world have come together… Will this cowardly people place its fate in the hands of this crazy daredevil? And will Pearl and her sarcastic friend, Oliver, succeed in saving the world?