Sabrina, Harvey, Valerie, and Libby have one week to redo their lame science project about space. But before they have a chance to begin, Sabrina finds a puzzle with a spell that transports them to Paris in 1783. Suddenly Sabrina and the three mortals find themselves captive in the barn of two crazy French hot-air balloon inventors. Enter the balloonist's niece -- and admirer of Harvey -- who helps the teens escape.