Thin Places.

One night a year, on the holiday Samhain, the spirit world and the mortal world were bridged. Historically, in Ireland, the Celts were able to reconnect and celebrate with loved ones who had passed. But it was not always safe; not all spirits are good. Some wanted to hurt the living and steal them back to the other side. To combat this, people created disguises in order to blend in with the supernatural. On one such night, against their father's wishes, three young siblings in the Irish countryside go out in search of their mother's spirit. They create masks for themselves and set off into the unknown.