The film is a romantic comedy that follows the adventures of Barney Lincoln and Angel McGinnis in the gambling hubs of London and the Riviera. Barney, a skilled gambler, achieves stunning wins at poker and chemin de fer by having access to marked playing cards from a Geneva factory used in all European casinos. Angel, the daughter of a Scotland Yard inspector named Manny McGinnis, takes notice of Barney's gambling and recruits him to play against a shady London character as part of a plan by Scotland Yard to financially ruin him.