Dak Bangla is a horror mystery drama. The movie revolves around an old building of a post office that used to be a palace of some prince years ago. The townspeople are sure that the building is haunted, and no manager has lasted long in the post office. A new man is appointed as a manager of this post office and he moves with his wife there. He moves into the building with his wife, and learns that some thugs have invaded this palace. Soon after, he finds out that there is a mummy walled in the dungeon of this building, which has something to do with all the deaths and other hauntings in the palace. Will someone be able to find out about the truth of this mummy?