GERTRUDE    Nay then, I’ll set those to you that can speak.

HAMLET         Come, come, and sit you down. You shall not budge.

You go not till I set you up a glass

Where you may see the inmost part of you.

GERTRUDE    What wilt thou do? Thou wilt not murder me –

Help, ho!

POLONIUS      [behind the arras]      What ho! Help!

HAMLET         How now! A rat! Dead for a ducat, dead!

[Kills Polonius.]          (3.4.16-23)

Gertrude’s steely too, frustrated and angry but not giving up: nay then, I’ll set those to you that can speak. If you can’t have a civil conversation with me then you’ll be explaining yourself to someone else, implicitly Claudius. Hamlet’s not giving up either, and he can be very physically threatening to his mother; an encounter which was called for on her terms and initiative is now being run on his: come, come, and sit you down. It can be (sarcastically) conciliatory, or he can force her to sit. You shall not budge; no, don’t you dare make a move (implicitly she has). You’re going to LISTEN to me. You go not till I set you up a glass where you may see the inmost part of you. You’re not going anywhere until there’s been some plain talking, until I’m done with telling you exactly what I think of you, showing you your true self. (Hamlet’s out of control, this isn’t about Claudius’s guilt in this moment, it’s all being coloured by his hatred of his uncle, his disgust at his mother’s marriage–his grief.) The arrogance of it, as well as the pain, a child lashing out, you’re going to listen to me for once. And Gertrude’s terrified, understandably, especially if he’s already started shoving, shouting, holding her down in a chair (or, inevitably, in the modern performance tradition, on a bed): what wilt thou do? She wasn’t at all prepared for this. Thou wilt not murder me—and there has to be enough threat, probably enough violence, to make this a real fear, in the moment. Help, ho! Is she calling for Polonius, does she even remember he’s there? is she calling for guards? That seems to be what Polonius is doing, rather than coming to her aid himself: what ho! Help! Noise, confusion, and Hamlet’s not thinking straight, but also perhaps thinks—entirely reasonably—that he’s been set up, that this is an attempt on his life. How now! A rat! What the hell’s going on? (Rats readily ran behind wall hangings and panelling; Hamlet’s also punning on arras, the generic term for a heavy textile wall hanging derived from Arras in northern France, where many were made; the town’s crest featured rats.) Dead for a ducat, dead! It sounds like an oath; it emphasises that this is think first, ask questions later; a ducat isn’t quite a pin’s fee, but it’s a low price for a life, as Hamlet stabs (or shoots), the alliteration striking dully. (The blade of a rapier or of many daggers would readily pierce cloth; their narrow blades were designed to penetrate clothing, and they were stabbing, not slashing weapons. But of course in the theatre it can be a trick retracting blade, which is easier with dagger than rapier.)

It is salutary to be reminded that Polonius is killed not even 25 lines into the scene…