Stanley is a troll with a magical green thumb, able to bring flowers and plants to life at a touch, which is forbidden in his home, the Kingdom of Trolls. When he is discovered doing so, the other trolls arrest him and take him to Gnorga, the queen of the trolls, who concludes that Stanley "gives a bad name to trolls everywhere" and demands that he be transformed to stone with her dark thumb (which is also purple when it glows). At the behest of her consort King Llort, Queen Gnorga instead banishes Stanley to Central Park in New York City where, after a series of mishaps, he ends up in a cave under the bridge.