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 streets,  the country's leading figures continue to bicker and fight, in their attempts to gain outright political control.

Meanwhile, following a desperate failed attempt to flee the country, a deeply despised King Louis 16th, and his equally unpopular 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 couples' lives, Cardinal Richelieu decides to continue as planned, with the  Masked Ball he was intending to hold in honour 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 over 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 obviously the real king, and that the corpse is just a ridiculous imposter!

With the future of France at stake, Richelieu realises 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 these terrible events escapes, and a panic takes hold of the city!