_Madame de Mazerolles_, a wealthy widow, is, in the first Act, robbed and brutally murdered by her stepson, _Roland_, a dissipated young man, who is incited to the commission of the crime by his wicked mistress _Sabine_. _Vidocq_, the great representative of the new school in detection (_circa_ A.D. 1820), is away at the time, and in his absence the investigation falls to his rival _Yvrier_, who belongs to the old school. In the chamber of death _Yvrier_ soon makes up his mind that the guilty person is one _Henri Lebrun_, a faithful and gigantic old soldier, much given to beating his breast with both fists and talking at large about his services to his country, his immaculate honesty and his domestic virtues. Suddenly _Vidocq_ enters. He discovers that the assassin has entered by a certain door because a cobweb has been disturbed, he picks up a red flower dropped by the assassin, he pours contempt on the crass stupidity of _Yvrier_--all quite in the best Sherlock Holmes style. But nothing comes of it all. Poor _Henri Lebrun_, still beating his breast with fists, is arrested, and after a painful interview with his only daughter (whom he discovers to have been the mistress of _George_, the son of _Madame Mazerolles_), he becomes sublime, accuses himself quite unnecessarily of the murder he had never committed, and is marched off to prison amid the execrations of the populace, the triumph of the crass _Yvrier_, and the loudly expressed determination of _Vidocq_ to bring the guilty to justice and save the life of the innocent _Lebrun_. Time passes. _Lebrun_, overwhelmed by an entire absence of proofs, is tried and condemned to death. It is the morning appointed for his execution. The curtain rises in the upper floor of a restaurant commanding an extensive view of the guillotine. The sight-seers troop in. First of all comes _Roland_, the murderer, disguised in black as a wicked Marquis, and accompanied by the infamous _Sabine_. _Hélène Lebrun_, the daughter of the condemned man, also troops in to slow music in black. There is a commotion at the door, and the obsequious innkeeper backs on to the stage ushering in _Milord Sir John Stilton_ and his son "_Shames_." _Sir John_ is dressed in an enormous green swallow-tailed coat with brass buttons, a striped yellow waistcoat, a pair of yellow knickerbockers, and stockings brilliantly striped with red and black. On his head he wears a low-crowned hat. In one hand he carries an umbrella, while a telescope dangles from his Shoulders by a strap. In short, he is _tout-ce-qu'il-y-a de plus Anglais_. His son _Shames_ is even more aggressively British. _Sir John_ orders lunch: "_vous donner moa bifteck_" is the obvious formula. _Shames_ concurs with a "Yehs, Pappah," which provokes roars of laughter. But stay, what is this? _Sir John_ takes _Shames_ aside: they talk in beautiful French. Can it be? Yes, by Heaven, it is the great _Vidocq_ with his faithful _Coco-Latour_! We breathe again, for now we know