Allow me to introduce you to Marjorie Mayweather, a well-heeled debutante who ventures on her Grand Tour to Italy in 1897, in the company of a distant cousin.
At their modest pension, Marjorie meets a dashing but aloof Captain Edward Grainger, esquire. She finds him stodgy and over-protective.
Straining against the constraints of conventional society and eager for adventure, Marjorie manages to get herself into a number of scrapes in which the begrudging Captain Grainger comes to her rescue. Unknown to Marjorie, Captain Grainger works for Lloyds, and is in pursuit of a notorious international jewel thief. His job is to assure the South Sea pearls of Mrs. Grace Parmeter are not pinched while she vacations in Tuscany. An informant has told Edward that the thief is a resident of Marjorie’s pension.
Enter the Honorable Freddie Clive-Bickerton who wishes for Marjorie’s hand and her fortune. He takes her to the opera in style and has the most impeccable manners.
Marjorie soon realizes it’s Edward Grainger who can be depended on.
When a stolen diamond bracelet is found in Marjorie’s opera reticule, the local police arrest her. Edward reveals his true identity and convinces the police that the culprit is another resident of the pension who has left in a hurry. Except the accused has an alibi, and Edward fears the real thief is a danger to the others and will strike again.
Knowing she’s spoilt Edward’s chances to catch the thief, Marjorie persuades her cousin to go with her to Grace Parmeter’s villa where they apply for work as housemaids so they can spy on her guests. They are hired because the lady is giving a house party and extra staff are needed. An angry Edward is one of the guests and so is fickle Freddie.
Marjorie does her best to uncover the thief, but her antics put the party into a terrible uproar.
In the end the thief is exposed, Edward is reconciled and Marjorie finds falling in love to be the grandest adventure of them all.