Claudius and Gertrude meet with Hamlet’s friends Rosencrantz and Guildestern, who they told to go to Elsinore to figure out why Hamlet was so strange. Rosencrantz and Guildenstern agree to help.
Polonius entered and said that he figured out the cause of Hamlet’s madness. But, first, the ambassadors have returned from Norway. He goes to get them. While Polonius is gone, Gertrude says that Hamlet’s madness probably comes from his father’s death and fast marriage to his uncle, Claudius .
Polonius returns with the ambassadors. They report that the King of Norway rejected Fortinbras , who promised not to attack the Danes. Norway then rewarded Fortinbras by letting him attack the Poles. Now Norway asked Claudius to give Fortinbras’ army free passage through Denmark on the way to Poland. Claudius agrees.

After a long talk about Hamlet’s madness, Polonius reads love letters that Hamlet sent to Ophelia. Claudius and Gertrude agree that love may be causing Hamlet’s behavior. Polonius proposes that they stage a meeting between Hamlet and Ophelia and spy on them to test his theory. Claudius agrees. Hamlet enters. The King and Queen leave Polonius alone to talk with him. Polonius speaks with Hamlet, who responds with statements about pregnancy, death and Denmark, Polonius, was confused and then exited.
Rosencrantz and Guildenstern enter. Hamlet greets his friends warmly, and tells them that Denmark is a prison. They disagree. He then says a long speech about the beauty of the world and nobility of man, all of which looks to him like dust and fails to please him. Hamlet asks why they’ve come. They say to visit him, but Hamlet angrily demands whether they were ordered by the King and Queen. Rosencrantz and Guildenstern admit they were.

Hamlet cheers up a bit when Rosencrantz mentions the arrival of a troupe of players (actors). Hamlet says his “uncle-father and aunt-mother” are wrong: he’s only insane when they are around. Polonius enters with the players. Hamlet mocks Polonius, but greets the players warmly. He asks the First player to act a speech about the Trojan queen Hecuba’s grief at the death of her husband, Priam. The Player does, and he does it well.
Hamlet tells Polonius to treat the players well and give them good lodgings, and privately asks the First Player to perform The Murder of Gonzago on the following night, with some extra lines Hamlet wrote himself. The Player agrees.

When Hamlet was alone he became so furious that the Player could get so emotional over dead Hecuba, while he couldn’t even bring himself to revenge his murdered father. Hamlet then comes up with a plan: he’ll have the players show a scene similar to Claudius’s murder of his father: “The play’s the thing wherein I’ll catch the conscience of the King”.