Charlotte Roberts is dead and her nephew and niece Grayson and Mia have moved to a new city with their great-aunt Leonne in Lagoon Haven, Massachusetts. They endure new schools and an eerie new childcare center that has evening and night children behaving strangely. Grayson meets Charlie Nelson who is an outcast who studies the bible on Saturdays with his grandpa Raymond. Both boys discover that the night children do not eat food and have sharp teeth and they never sleep at night. Charlie and Grayson discover that the center is hiding an ancient creature underneath the basement and they work together with their grandfather and a journalist to stop the night creatures from taking over the city.