Nicholas receives a new monster game on his 8th birthday. During the night, the monster comes alive in his closet. Lucky for him, this monster is a friendly one. But it is always hungry and has a special appetite for socks. Nicholas calls his best friend William and now the boys need to learn what it means to take care of a monster. But how long can Nicholas hide his monster from his family? And what happens if he brings it to school? Perhaps the monster can help them scare away the bully "Soap," who is always teasing them...