Aperture Kids and the Mysterious Neighbor (2021) on Netflix

Plot summary

Alex Hamilton lives with his mother and his younger sister, Jessica, in a rough part of town. His parents have recently separated, and he holds his mother responsible for leaving his father and for the move. Odd things start happening at the house beside them, and Alex finds out that the man living there is suspected of a serious crime. Believing the neighborhood is unsafe, he asks his mother to take the family back to his father. She will not. Alex then turns to Christina, a girl who lives nearby, and to Jessica, and the three of them set out to look into the claims about the neighbor. Their outings grow more dangerous.