Just as Gertrude appears convinced by Hamlet's excoriation, the ghost of Old Hamlet reappears and tells Hamlet not to behave so cruelly to his mother, and to remember to carry out revenge on Claudius.
Gertrude perceives her son discoursing with nothing but air and is completely convinced of his madness.
Though skeptical at first, Horatio sees the ghost and decides to report its appearance to Hamlet.
Meanwhile, a new king of Denmark has been crowned: Claudius, Old Hamlet's brother.
Rosencrantz and Guildenstern's attempts to discover the reason for Hamlet's madness are met with evasion and witticism.
Meanwhile, Polonius hatches a theory of his own: he thinks that Hamlet is insane due to Ophelia's rejection of his love.He arranges to test his theory by setting Ophelia on Hamlet when they are apparently alone and then observing the proceedings with Claudius.Hamlet's only consolation appears to be the coming of a troupe of players from England.She sings childish and bawdy songs and speaks nonsensically.Laertes soon returns to Denmark with a mob in tow, demanding an explanation of Polonius' death.Hamlet asks the player's whether they could play a slightly modified version of a tragedy.We realize that Hamlet plans to put on a play that depicts the death of his father, to see whether Claudius is really guilty, and the ghost is really to be trusted.Claudius has taken Old Hamlet's widow, Gertrude, as his wife.We watch their marriage celebration and hear about a threat from the Prince of Norway, Fortinbras, which Claudius manages to avoid by diplomacy.Horatio tells Hamlet of the appearance of the ghost and Hamlet determines to visit the spirit himself. Hamlet questions the ghost, who beckons Hamlet away from the others.Meanwhile, the court adviser, Polonius, sends his son, Laertes, back to Paris, where he is living. When they are alone, the ghost reveals that Claudius murdered him in order to steal his crown and his wife.