The Devil Is an Ass is a Jacobean comedy by Ben Jonson, first performed in 1616, first published in 1631, and based on the events of the famous Leicester Boy Witch Trial.
The initial publication of the play was somewhat irregular, in that Jonson intended to include it in a second folio collection of his works in 1631, but scrapped the plan when he was dissatisfied with the printing.
Pug pleads his case, however, and Satan sends him into the world, specifically to plague an eccentric and foolish gentleman named Fabian Fitzdottrel.
Fitzdottrel is obsessed with the idea of meeting a devil; he has consorted with magicians and conjurers (Simon Forman among others) in hopes of encountering an imp who will aid him in the discovery of buried treasure.
In addition to his main mania, Fitzdottrel has subsidiary obsessions: he dresses his beautiful young wife sumptuously, but clothes himself in second-hand garments, which he wheels and deals over with enthusiasm.
His reputation for eccentric foolishness has made Fitzdottrel the target of a host of confidence men, who fall out into two groups: on the one hand, the young gallant Wittipol and his friend Manly, and on the other the "projector" Merecraft and his henchmen, Ingine the broker, Lady Tailbush, Guilthead the goldsmith, Everill and Train and others.
In the sympathetic court of Sir Paul Eitherside, Merecraft plans to get the legal documents dismissed and restore Fitzdottrel to the control of his own estate, so the cheating can continue.
But word arrives of the satanic doings at Newgate; and Fitzdottrel, realising that Pug, "Deville," had been a devil after all, is so beside himself that he abandons the pretense of bewitchment and spills the beans.