I'm looking for a movie which, I think, is from the 80's. An old woman wears a bracelet which controls or calls an entity/force when she is in trouble. Some villains attack and kill her. The entity/force takes revenge upon her attackers. Somehow, the bracelet separates from her wrist. Later some young people find her. One boy/girl picks up the bracelet and it locks itself to his/her wrist. They don't know about the entity/force. The entity/force starts killing people. If memory serves me right, some of the action takes place in a museum. From then on they try to remove the bracelet. I don't recall how the movie ends. Thanks.