Never tell all you know-not even to the person you know best.

London, 1919: Out of work and out of money, Prudence "Tuppence" Cowley and Tommy Beresford renew their friendship and decide to form their very own "espionage for hire" company called The Young Adventurers, LTD. The sum of their ages not exceeding 45, the enterprising young duo doesn't allow the world's view of their youth to obstruct their ambitions. Seemingly out of nowhere, a one Mr. Whittington solicits Tuppence for work after overhearing her conversation with Tommy. Despite her severe reservations toward Whittington, Tuppence accepts and together she and Tommy are pulled into a world of espionage, skullduggery, and danger.