Title: The Secret of Sigma Seven
Description: The aliens are invading! No, they're not from another galaxy. They're not even from Mars. They're from Hollywood! A science fiction convention has come to Bayport, and movie director Simon Devoreaux has lost his billion-dollar baby: the film of his latest blockbuster has dematerialized before his eyes.
Subjects: Children's fiction, Extraterrestrial beings, fiction, Science fiction, series:HardyBoys, collectionID:HBMS3, Mystery and detective stories, Hardy boys (fictitious characters), fiction