A gremlin – a little purple creature who loves to dismantle electrical stuff and cause chaos – is loose. Jake and Grampa try to stop him when it drives a subway but Jake is too embarrased to sing the gremlin a song that will make it go to sleep, so it gets away. Jake accidentally takes it home while his mom is planning the wedding of the century. The little creature gets to the wedding and wrecks havoc – and Jake needs to stop it.