Mr. John Vansittart Smith is a student of Egyptology who travels to France to see some papyri in the Louvre Museum. Tired from his visit, he sits in a corner of the museum and dozed. When he wakes up, the museum is closed and he is locked inside. Trying to get out he meets a strange man who seems to perform a ritual on a mummy. The curious man tells his story:
His name is Sosra and he was born 3500 years ago in Egypt. He was a priest of the god Osiris and discovered a remedy against death. He used it and shared it with his assistant, Parma. He wanted then to administer this elixir to his fiancee, Atma, but she died just before. He went desperate because he couldn't join her in the afterlife. So he wanted to become mortal again. Parma reported him that he had found an antidote but he had decided to use it for himself so he can die and meet Atma beyond. Sosra realized that the antidote was in the ring of Thott but Parma had hidden it and he took his secret to the grave. 3500 years later the mummy of Atma is found by French archaeologists and repatriated to the Louvre. Sosra succeed to be hired in the museum, found the Atma sarcophagus and got the ring containing the precious elixir.
At the end of his incredible story Sosra accompanies Vansittart to the exit. Two days later he learns in the newspapers that a man was found dead in the museum entwined in the arms of a mummy.
