In an international car rally, competitors must travel from various points in Europe to Monte Carlo, then race their cars. Things are complicated by smuggling, cheating, honor, inventions, medicine, and love at first sight...

In the 1920's, the contestants for the annual Monte Carlo Rally (a 1,500-mile automobile endurance race) arrive at five different starting points throughout Europe. Among those competing are Chester Schofield and Sir Cuthbert Ware-Armitage, the owners of a British auto factory. Chester, an American gambler, won his half of the factory from Cuthbert's late father during a poker game, and the two men have entered the contest on a winner-take-all basis. Other entries include Maj. Digby Dawlish and Lieut. Kit Barrington, a pair of British Army officers and would-be inventors from India; Angelo Pincelli and Marcello Agosti, two womanizing Italian policemen; Schickel and Otto, German convicts who are unaware that the owners of their car have hidden stolen jewels in a spare tire; and three French feminists led by Marie-Claude, a doctor. As the race begins and the contestants battle the elements, the hazardous roads, and each other, they run into countless calamities. Chester, due to the treachery of Cuthbert, loses his co-driver and is forced to go it alone until he meets Betty, a pretty socialite; Schickel and Otto's car becomes entangled in a series of winter sports and ends up hanging from a ski lift; all the parties converge on a French Alps resort and spend a sleepless night because of room mixups; the French feminists and the Italian policemen push each other in and out of snow drifts; the Germans discover the stolen jewels but decide to remain in the race; and Betty nearly drives herself and the sleeping Chester over a frozen waterfall. Eventually, after the feminists have dropped out to aid people injured in a snowslide, the battered cars and drivers arrive at Monte Carlo. Because they all have demerit points, however, they must now compete in a final race down a winding mountain road. Dawlish and Kit are defeated when their rocket propulsion invention blows up their car; Cuthbert is disqualified for stealing a tire; and Schickel and Otto are arrested and marched off in handcuffs. Although the Italians are declared the victors, they gallantly renounce their trophy in favor of the feminists. Chester, still asleep, is pushed over the finish line by Betty, his own personal prize.