Leo Lennox is in big trouble. Actually, every Turner on the planet is in big trouble: a deranged scientist is threatening to expose their secret world and destroy them all. With help from a pair of guerrilla gorillas (and their incredible inventions), his nerdy friend Ernie, and his annoying-but-sort-of-all-right older sister Abbie, Leo must criss-cross the world to stop the mad doctor before he serves up the full buffet of doom to Turners everywhere. If he can't, the planet won't be just a little bit doomed - it'll be fully doomed!