The Hardys have come to the Hawaiian Islands to join in a scientific research project at the Mauna Kea Observatory. They have won the chance to witness a once-in-a-lifetime event -- a total solar eclipse. But at the very instant day turns to night, the excitement suddenly turns deadly. The boys find the expedition leader...murdered!

Frank and Joe begin a research project of their own and make some shocking discoveries: The expedition has long been plagued by personal hatred, professional jealousy, and financial greed. They have plenty of theories but must come up with some hard facts. For evil lurks in the shadows...and more violence could erupt at any moment!