It’s the summer of 1753 and the city of Frankfurt in Germany has a distinguished visitor – the delectably conceited French philosopher Voltaire – who, having recently fled the court of Frederick II, King of Prussia, after a misfortunate falling-out, is looking for refuge on his way back home to France. Accompanied by his very Italian manservant, Collini, Voltaire has a sensitive manuscript in his possession – a book of poetry, written by King Frederick himself – a book which, if it were exposed to the world, would make the King appear sensitive and weak and make it impossible for anyone to fear Prussian militarism. The crafty philosopher knows this all too well and, in a delightful act of revenge, can’t wait to publish the King’s manuscript and embarrass him before all the world.

Alas, Voltaire’s plan quickly goes awry, thanks to the Hitlerian Baron Franz von Freytag, representative of the Prussian King, who, bolstered by his secretary Dorn and by an obsessive love of authority (especially the very, very tyrannical kind), is on a mission to hunt down Voltaire and rescue the King’s manuscript. Voltaire soon finds himself trapped in Frankfurt and at the mercy of the Prussian authorities – a situation which is not helped by the unexpected arrival of Mademoiselle Denis, the philosopher’s buxom, sex-obsessed niece – or, indeed, “niece.” Nor does Voltaire manage to find any respite from a wily, nasty, money-grubbing German shrew, Frau Schmidt, the wife of the Prussian consul, who would sell out her mother for a dime – or, indeed, a philosopher for much more.

After a series of escapades, Voltaire is arrested by the blustery Baron von Freytag and imprisoned in the house of his now-nemesis, Frau Schmidt – imprisoned, indeed, for over a month, since, after all that, the baggage with the King’s manuscript is held up in Leipzig and has yet to arrive in Frankfurt. In the meantime, hankering for freedom, Voltaire cleverly plots his way free of Frau Schmidt’s house, using sophistry to drive Freytag’s secretary, Dorn, to suicide, and then dressing up Collini as the deceased Dorn, through which an artful plan of escape is devised. The plan is foiled when Baron Freytag makes an early return and, after a series of events, finds himself locked in Frau Schmidt’s house by the wily philosopher, as Voltaire, Mademoiselle Denis, and Collini make a b-line for liberty.