The year is 1791 and France continues its headlong slide into a state of anarchy and terror. As the starving French people riot openly in the blood-stained streets, leaders of the country's various rival factions continue to quarrel and fight in their attempts to seize outright control.

Meanwhile, following their desperate failed attempt to flee the country, the deeply unpopular King Louis 16th and his equally despised wife, Marie Antoinette, have been taken to the Bastille fortress, where they are now being held under guard, "for their own safety".

In a brave attempt to inject a small degree of normality back into the royal couple's lives, Cardinal Richelieu decides to continue as planned, with the Masked Ball he was intending to hold in honor of the King’s 40th birthday - albeit on a much smaller scale, with just the jail’s four current residents, and each of their guests, in attendance.

However, with just an hour to go until the party begins, Richelieu is horrified to discover King's lifeless body lying slumped across his dressing room table, having been poisoned with some form of deadly toxin!
Confusion soon replaces shock, however, when a second ‘living and breathing’ Louis then appears, identical to the first, and claims that he is the real king, and that the corpse is obviously just a ridiculous impostor!

With the future of France at stake, Richelieu realizes he must enlist the help of all those attending the ball, if he is to catch his killer and unravel this mystery, before news of the terrible events escapes, and a panic takes hold of the city!