Jill Jekel's life has been turned upside since the police knocked on the door to let she and her mother know that her father was murdered. Good girl Jill soon learns that her father was keeping secrets and depleted her college fund. When her chemistry teacher Mr. Messerschmidt informs Jill and two of her classmates about a scholarship competition, she sees a way to possibly fund her college dreams.
Tristan Hyde is a brooding, gorgeous young man in Jill's chemistry class. He and his psychiatrist father are in the U.S. from Britain so that his father can do research at the local university. Mr. Messerschmidt attempts to push Jill and Tristan together to work on the scholarship competition. They could play off their names, Jekel and Hyde, and tie into the book The Strange Case of Dr. Jekyll and Mr. Hyde. Jill begins to think about a Jekel-Hyde combination and the mysterious locked box in her father's office, the box Jill has been warned never to touch.
Jill takes up her case with Tristan to enter the competition conducting an experiment based on the book. Jill tells Tristan that her dad believed the Jekels were descended from Dr. Jekyll and that in the box are the opriginal documents detailing the famous experiment. Tristan agress to work with Jill because he believes that he is descended from Mr. Hyde and that he too is an out-of-control monster just under the surface. If their experiment works, Tristan hopes thathis sanity and life can be saved. But what happens when Jill accidentially ingests some of the formula? Will she decide that being a bad girl might not be so bad after all, even if it means risking Tristan's love?