Hamlet teaches three of the players on how to act. His lecture focuses on how to avoid overacting, suiting action to word and word to action. Hamlet has already told Horatio what the Ghost said, and now reveals his plan: the play to be put on, will mirror the Ghosts’ description of Claudius’s murder of Hamlet’s father. If Claudius looks guilty while watching it, then he is.
Claudius, Gertrude, Polonius, Ophelia and others arrive to watch the play. Hamlet tells Horatio he’s now going to act insane.

The players enter and first act out a dumbshow (a short silent play that shows what the longer play is about). The players then begin to act the full play. As the plot becomes clear, Gertrude and Claudius become uncomfortable. Hamlet mocks them, while continuing to say sexual puns at Ophelia. Claudius asks the name of the play. Hamlet says, “The Mouse-trap.”
When the villain in the play pours poison into the king’s ear, Claudius jumps from his seat, calls for light, and rushes from the room. Hamlet’s plan worked. He tells Horatio that this proves the Ghost was telling the truth. Rosencrantz and Guildenstern enter and say that his mother wants to see him. Hamlet agrees to go, but furiously tells them they cannot “pluck out the heart of his mystery” or play him like a flute. Polonius enters, repeating Gertrude’s request to see him. Hamlet pretends to see odd shapes in a non-existent cloud. Polonius also pretends to see the shapes to make him feel better

Everyone leaves but Hamlet, who says to himself that he could “drink hot blood”, but forces himself to remember not to hurt his mother.