Charles Christie

Charley Wyckham and Jack Chesney pressure fellow student Fancourt Babberly to pose as Charley's Brazilian Aunt Donna Lucia. Their purpose is to have a chaperone for their amorous visits with Amy and Kitty, niece and ward of crusty Stephen Spettigue. Complications begin when Fancourt, in drag, becomes the love object of old Spettigue and Sir Francis Chesney.

Robert Castleback is in possession of secret papers which could bring a certain prince to power under conditions which would make Castleback a ruling force in Europe. Master crook Arsene Lupin becomes aware of Castleback's bid for power and, in the interests of France, begins a search for the plans.