The "girl" of the title was played by Hazel Dawn, a popular stage actress who briefly enjoyed a flourishing film career. Dawn plays Miss Shipley, an American girl vacationing in France. Our heroine finds herself the romantic bone of contention between two "men of the world" (William Roselle and Hal Clarendon), who end up fighting a duel over her affections.

On the advice of his friend Pendleton, Ashton Kirk, a scholar and amateur detective, pays a visit to a house whose occupants, Charles Cramp and his sister Grace, complain of strange happenings involving Mexicans. Discussions with Ashton's agent in Mexico reveal that Cramp's father was once an engraver, who, in desperate need of cash, had agreed to supply Alva, a notorious thief, with forged currency plates. After a change of heart, Cramp refused to deliver the plates to Alva, and now Cramp's aunt, Miss Hohenlo, has come to her brother's home to find them herself. The clever Ashton realizes that the Mexicans are cohorts of Alva's and eventually uncovers an elaborate signalling and tunnel system used by Miss Hohenlo and Alva to locate the missing plates. Deciphering a message announcing the time and place of the arrival of the Mexicans, Ashton and his aides hide themselves in the house cellar, capture the thieves and destroy the plates.

Ashton Kirk is a wealthy and scholarly young man who solves mysteries that have the police puzzled. Stella Morse asks Kirk to find out who is threatening her uncle, Dr. Morse. Morse has a copy of a secret treaty between Russia and the United States that was made during the Russo-Japanese War. When the Doctor is murdered Kirk takes on the case. Japanese spies have been trying to purloin the treaty to ruin relations between its country and America. Kirk manages to get the treaty himself and prevents a war from breaking out.

Mici is the middle of seven sisters, who all believe if a younger sister marries first, the oldest sisters all doomed to be old maids. The elder sisters conspire to have the younger, pretty Mici sent away to a convent school. Mici manages to slip away and attend a fancy party, where she meets Count Horkoy. They fall in love and to the delight of Mici's sisters, the Count also finds suitable husbands for all of them.