In the beginning, the ship Lusitana has been torpedoed and a stranger has given a young girl a packet contaning an important document. The stranger dies, and the girl, whose name is Jane Finn, disappears, and the packet is forgotten. Until, that is, a labor unrest starts in England and if the papers fall into the wrong hands it could prove deadly to the government. Tommy Beresford and Prudence Cowley (nicknamed Tuppence) know nothing of this when they unexpectantly meet. They go to a restraunt and discuss what's been going on in their lives since they last met. Discovering that they're both currently unemployed, they come up with the idea of becoming adventurers,"willing to do anything, go anywhere." After they depart, a man named Mr. Whittington approaches Tuppence, and he leads her to his office. He overheard their conversation, and he wants to propose a job offer to Tuppence. He wants her to go to France to a place called Madame Colombier's for about three months. When he asks her what her name is, she doesn't want her father to think anything bad, so she says,"Jane Finn." Immeadiatly, Mr. Whittington gets very angry and says, "How much do you know? And how much do you want?" Tuppence manages to get fifty pounds off him, then she leaves. She and Tommy discuss the situation at an expensive restraunt and decide to try and find out who Jane Finn is. The next day they recieve two letters: one from a Mr. Carter, and one from a Julius P. Hersheimmer. They decide to tackle Mr. Carter first, and he happens to be from the Intelligence. They tell him all they know, and he tells them about Jane Finn-and their adversary Mr. Brown. Mr. Brown is a non-descript man who is behind the labor unrest and is causing alot of trouble. Their task is to unmask Mr. Brown, find Jane Finn, and recover the papers. Now they must face unspeakable danger to do this, but it is a race for time. They enlist the help of an American millionare named Julius P. Hersheimmer, who is her cousin. Who will win this race? Will it be Mr. Brown and his organization, or three ametuer adventurers looking to save their country?