Little Molly lives with her parents in Monsterland, a quiet Monsters’ Village made of hills, volcanoes and geysers. There’s quite a stir in Monsterland: little monster Molly is going to get a brother or sister. The baby, like all monsters, must come into the world in the far away Egg Island. Molly is too young to go there but, at some point, she decides to rebel and tries to reach it with her best friend Edison.