Once again, the plumbing at Tawcester Towers is causing consternation for the Dowager Duchess, so - unusually for her - she gives her blessing for Blotto to take part in the 'Great Road Race' in his beloved Lagonda ... so long as he wins. The first prize of 10,000 pre-War sovereigns will help towards repairing the leaky ancestral home.
Blotto elects to take chauffeur Corky Froggett as his spare mechanic, while Twinks is despatched by her mother to the Highlands, to paint water colours and bag herself a wealthy husband. But, on the morning of the race's start, enfeebled by food poisoning, Blotto and Corky are forced to employ an extra mechanic on their team - a slender, blonde and rather attractive young American... named Ronald.
So Blotto and his team are pitted against Europe's finest, in a race which takes them through France, across the Alps, to a finish line at the Colosseum in Rome. Among the competitors are Florian Carré-Dagneau, indulged son of the race sponsors, Count Daspoontz from Germany, and the Italian Enrico Parmigiano-Reggiano. All want to win the race, and all want the prize money and all - with the exception of Blotto and his team - will resort to dastardly deception and fiendish sabotage to ensure Blotto's Lagonda is not the first car over the finishing line...