The Chalk Line (2022) on Netflix

A couple temporarily adopts a young girl that they found wandering around alone in the high road.

Paula and her husband are coming back from a dinner when they suddenly find a young girl wandering around in the high road. Two weeks later, after seeing that no one is claiming her back, the two decide to let her stay in at their home temporarily, and so give a twist to their love life in the process. But it won't be that easy, since the girl lives obsessed with the fantasy that a monster will come out and punish her if she ever steps out of a chalk square painted in the floor. After the strong bond created between the two, Paula beings a road down a dark path to try and discover the girl's enigmatic past.