Volpone, childless and rich, and his servant, the parasitic, Mosca, play a cunning and farcical game of deceit with three ‘friends’ who are each determined to become Volpone's sole heir. Volpone decides to feign a fatal illness to encourage the three men to shower him with valuable gifts in the hope of gaining his favor and, ultimately, his money.
First up is Voltore, whom Mosca falsely promises is the sole heir. Corbaccio arrives next, and Mosca advises him to go home, disinherit his own son, and leave his fortune to Volpone. If he follows this advice, Mosca declares that Volpone would leave his fortune to Corbaccio. The last to arrive is Corvino. Mosca slyly convinces him that his beautiful wife, Celia, should be allowed to sleep by Volpone's side as a cure for the supposedly dying man, after which Corvino will become Volpone’s sole heir. In his final act, Mosca tells Bonario, Corbaccio's son, about his father’s plans to disinherit him, and he promises to lead Bonario to a place where he can witness his father's betrayal.
As Volpone and Mosca’s wicked plans come to fruition, the confusion mounts. Bonario arrives to witness his father inheriting him but, instead, he rescues Celia from Volpone’s attempts to rape her. Mosca and Volpone, in terror of exposure, bewail their ruined plot and convince Voltore, a lawyer, that Bonario had mistaken Celia's visit and had burst upon Volpone and threatened to kill him. Taken in by their lies, Voltore promises to keep Bonario from accusing Volpone of rape and orders the young man arrested. In the ensuing trial, Mosca uses his powers of sly manipulation to ensure that the truth is well buried by false evidence given by the men he and his master have duped.
When the trial is over, Volpone sends out an announcement that he is dead and that Mosca is his heir. Mosca then greets all the enraged men as he sits in Volpone's house taking stock of all his newly acquired wealth. Volpone, however, has disguised himself in hopes of escaping from Venice with his loot.
However, when Mosca refuses to relinquish Volpone’s fortune, Volpone goes to the court and exposes the greedy behavior of Corbaccio, Corvino, and Voltore, as well as revealing Celia and Bonario’s innocence. All the conspirators including Volpone and Mosca, are sentenced by the court, Bonario is restored to his father's inheritance, and Celia is allowed to return to her father after being betrayed by her husband.