When competition for lucrative prizes ranging from money to placement on the Olympic Team escalates to the point where one desperate participant drugs horses at the River Heights Horse Show, Nancy, Bess, and George track clues to identify the culprit.
When Nancy, Bess, and George continue their journey and board a train bound for Denali National Park, they become aware that danger has followed them and Nancy worries her undercover status has been discovered.
Attending the annual Greek mythology gala at Oracle College, Nancy, Bess, and George race to assist when a student falls from a balcony in the middle of her speech, an accident the sleuthing trio links to collegiate sabotage.