The Greenfield Museum is holding a special exhibit about ancient Egypt, and the main attraction is a 4,000-year-old mummy. The Aldens are helping the museum curator set up the exhibit and learning about life in ancient Egypt. But the longer the Aldens are around the mummy, the more things go wrong. As the children search for the cause of all the bad luck, everything points back to the spooky sarcophagus. Has the museum been struck by a curse from the ancient mummy?