The Bogeyman (2002)

Original title: El hombre del saco

When 10-year-old Nemo's mother suddenly dies, the boy is forced to go live with his maternal uncle's family. They are cordial and treat him well, but his 12-year-old cousin, Iván, begins to tease and tell him stories about the Bogeyman and how he'll come and get him if he doesn't behave. At first young Nemo doesn't believe the stories, insisting that Iván is just making things up...