Tommy Beresford and Tuppence Cowley, two unemployed school chums, bump into each other in London and agree to become the "Young Adventurers," who will go anywhere and do anything, according to their ad. Soon they are involved in a complex plot involving the sinking of the Lusitania, British Intelligence, false identities, kidnapping, and poison. The two sleuth's partnership is cemented when they solve the fast-paced case and make marriage their next collaboration.