Set in 1919 London and various other outlying locales throughout Britain, young couple Tommy Beresford and Prudence "Tuppence" Cowley, out of work and money, form the "The Young Adventurers, Ltd." planning to hiring themselves out as "adventurers ... willing to do anything, go anywhere ... no unreasonable offer refused." Being overheard by Mr. Whittington, Tuppence is offered a comfortable position, only to be rejected after she gives her name as "Jane Finn", a name Tommy overheard when he and Tuppence earlier entered Lyons for tea and a bite and were walking to their table ("funny scraps one does overhear"). Lyons was the same restaurant at which Whittington overheard Tommy and Tuppence's plan for their new "joint venture." Whittington becomes suspicious of Tuppence, believing her to be blackmailing him. The meeting ends abruptly with Tuppence receiving money with the understanding that she will refrain from using her, albeit nonexistent, knowledge. Convinced that they can get further money out of Whittington if they play their cards right, Tommy and Tuppence prepare to shadow him, only to discover that he has closed his office and disappeared without a trace. His behavior indicates to them that there is another angle to the story. To find out, they place an advertisement, asking for information regarding Jane Finn.