The Secret Adversary

In 1919 London, demobilised soldier Tommy Beresford meets war volunteer Prudence "Tuppence" Cowley, both out of work and money. They form "The Young Adventurers, Ltd", planning to hire themselves out with "[n]o unreasonable offer refused."[4][5] They are overheard by Mr Whittington who follows Tuppence to offer her a position. He is shocked when she gives her name as "Jane Finn". Whittington sends her away with some money, then disappears without a trace. They advertise for information regarding Jane Finn.