Peregrine, disguised and accompanied by three merchants, enters Sir Politic's house. His design is merely to frighten, not to harm, Sir Politic. The merchants would rather ship him to Aleppo or some other port. Peregrine instructs them to wait until he gets into an argument with Sir Politic before rushing into the room.
As the merchants leave, Peregrine tells a female servant to announce to the English knight that a merchant, "upon earnest business, desires to speak with him." At first, Sir Politic sends word that grave affairs of state occupy him. Peregrine supposes that he is trying to make sausages without one of the ingredients. Finally, Sir Politic deigns to give the disguised Peregrine an audience.
Sir Politic informs the merchant that he has been busily engaged in writing an apology to his wife; she still believes that Peregrine was a disguised prostitute! Peregrine the merchant has a better theory about Peregrine the pilgrim: Peregrine was a Venetian spy who reported Sir Politic's plot "to sell the state of Venice to the Turk." Sir Politic becomes distraught. Alas, he has no such plot, only notes drawn from playbooks. Merchant Peregrine volunteers to have Sir Politic smuggled aboard a boat to escape capture. A knock at the door nearly gives the English knight a heart attack! His playacting is causing him serious trouble. Suddenly, he remembers an old invention: He puts a shell over his back and tries to behave like a turtle! Peregrine helps him into this foolish contraption and hurries off to burn Sir Politic's playbook notes.
The three merchants, on cue, burst upon the scene. They ask Peregrine who he is, and he replies: "I'm a merchant, that came here to look upon this tortoise." He points to the trapped Sir Politic and the others take up the joke. Peregrine says it is a fish but that one may strike it and tread upon it. They proceed to prod the foolish knight; Sir Politic gallantly, if uncomfortably, tries to keep up the disguise. Finally, Peregrine and the merchants pull off the shell and mock the gartered knight. Peregrine unmasks and tells Sir Politic that they are now even. The merchants have had their laugh, and Peregrine, apologizing to Sir Politic for the funeral of his papers, departs with his accomplices.
Sir Politic seeks out his lady and is told that she, too, is in need of a physic. He determines to shun this place and climate forever.
Once again, Jonson holds his audience in suspense by interrupting the main action of the play in order to resolve the action of the subplot. The subplot action closely parallels the action of the main plot. In fact, it suggests the resolution of the main action.
Unlike the main-plot characters, however, Sir Politic is guilty only of playacting offstage. He is really a very dull fellow, afraid of his own shadow, who dreams of an adventurous life. He is a fool, but a harmless one. His trouble with Peregrine is really brought on by his wife. She subjected Peregrine to a tongue-lashing that produced in the English tourist a desire to revenge himself on Sir Politic.
It is interesting to note that Sir Politic sees fit to employ a disguise. As we have seen, Act V is heavily larded with disguises. Jonson is obviously making fun of the English theatrical penchant for disguise. Sir Politic's tortoise shell is a work of genius! Peregrine's burning of the incriminating playbook notes compounds the theatrical irony. It is as if Jonson were saying that these silly devices could be done away with if only all promptbooks could be destroyed.
Ultimately, Sir Politic is trapped in his disguise. Is this intended to suggest that Volpone is trapped by his own disguise? It appears significant that Sir Pol chose the slowest possible animal to imitate, for it makes his escape impossible.
When Peregrine and the three merchants uncase their quarry, they are mimicking the final unmasking of Volpone in the last scene of the play. Since those watching the play fully expect Volpone to be discovered, the present scene merely whets their appetite for the event. And so Sir Politic Would-be is gently, though somewhat rudely, purged of his foolish humour.
While maintaining audience suspense about the main plot's resolution, Jonson has neatly tied up the subplot. The audience knows that Sir Politic and his wife will not show up at the courtroom. They have already received their punishment.