Horatio, Marcellus and Bernardo see the ghost of Hamlet's father. They decide that the only way to get the ghost to talk is to bring Hamlet.
Horatio and Marcellus come back the following night with Hamlet. Hamlet talks to his father. The ghost tells Hamlet that his death was not an accident. He was killed by his brother!He tells Hamlet to take revenge for his untimely death.
Hamlet has started to act crazy and no one knows why. Polonius says it is out of love for his daughter, Ophelia. The King and Queen don't really think that is the cause but they figured they should try Polonius's theory out. Hamlet is not actually going mad, but has a plan to expose his uncle
Hamlet has a group of actors preform a play in which a man kills the king, but Claudius proves he is guilty by calling off the play. Now Hamlet knows he can kill Claudius without guilt.
Hamlet has a conversation with his mother and Polonius spies on them in an attempt to learn why Hamlet is crazy. Hamlet, thinking the spy is Claudius, kills him.
Polonius's son Laertes stabs Hamlet with a poison blade and kills him, but not before Hamlet is able to kill Claudius with his sword and poison.