When the young American, Henry Adam accidentally finds himself alone and penniless in London, he unwittingly becomes the subject of an astounding bet between two brothers. He is presented with a bank note for one million pounds, to use as he pleases for a month. One brother believes the note will prove useless to him. The other believes that, even though nobody will be able to offer him change, the American's mere possession of the bank note will mean that plenty of people will offer him credit, believing him to be wealthy.

But as Adam begins his strange adventures in London society, the tale takes an amazing twist...