A penniless seaman Henry Adams gets caught up in an unusual wager between two wealthy, eccentric brothers, Oliver and Roderick Montpelier. They persuade the Bank of England to issue a one million pound banknote, which they present to Adams in an envelope. Oliver believes that the mere existence of the note will enable the possessor to obtain whatever he needs, while Roderick contends that it would actually have to be spent for it to be of any use.

At first, Adams is mistaken for an eccentric millionaire and has no trouble getting food, clothes and a hotel suite on credit, just by showing his note.The story of the note is reported in the newspapers, Adams is welcomed into exclusive social circles.

Then the Duke of Frognal hides the note as a joke. When Adams is unable to produce the note, panic breaks out amongst the shareholders and Adams" creditors. All is straightened out in the end, and Adams is able to return the note to the Montpelier brothers at the end of the month.