Much like her narrative feature debut “Atlantics,” “Dahomey” blurs the line between life and death. Giving voice to one of the returned artifacts, Diop imbues the documentary with the feel of a ghost story. The artifact, known only as 26, is a carved statue of wood and metal that observes its own journey from France back to its homeland in Benin. Its voice is low and raspy, reflecting its age and hidden wisdom.