Prince Hamlet's father, King Hamlet of Denmark, has recently passed away and the throne taken by Hamlet's uncle, Claudius, who has also married his dead brother's wife, Gertrude, with a speed that has deeply upset Hamlet. He is not coping well with his father's death. The death of the monarch has come at a time of great fear in Denmark; King Hamlet had defeated King Fortinbras of Norway in battle some years ago, but the countries were rarely at peace and a Norwegian invasion was a constant threat. Prince Fortinbras, the dead king's son, is rumored to be planning an attack.
The court gathers the next day and King Claudius chastises Hamlet for continuing to grieve for his father. He refuses to allow him to return to school in Wittenberg. Hamlet is in despair and feels his mother has betrayed both his father and himself. He learns from Horatio that whilst at the castle of Elsinore, his father's ghost had appeared to them, and he vows to see the ghost himself.
Polonius' son, Laertes, has received permission from Claudius to go to school in France, but before he leaves his sister Ophelia tells him that she has feelings for Hamlet. Laertes orders her to rebuff any advances that the prince might make.
The ghost of King Hamlet appears to the prince that evening on the rampart; he tells his son that he was murdered by Claudius, and he asks his son to avenge his death. Hamlet agrees immediately and the ghost vanishes. Hamlet comes up with a plan; he will pretend to have gone mad and he swears Horatio to secrecy, but he is secretly worried that the ghost might not be giving him reliable information.
Hamlet arrives at Polonius' door behaving in a very erratic manner. Polonius believes it is heartsickness and love for his daughter that is causing Hamlet to behave this way and decides to tell Gertrude and Claudius about the incident. However, he cannot inform them straight away as he plans to because when he arrives at court the King and Queen are welcoming two friends of Hamlet, Rosencrantz and Guildenstern, to Elsinore. Gertrude asks the students to find out why Hamlet seems to be losing his mind. As they talk, a messenger from Norway arrives to inform Claudius that the King of Norway has censured Prince Fortinbras for trying to re-fight his father's battles and agitate against Denmark. The troops that he had readied to invade Denmark will be sent to Poland instead although they will have to travel through Denmark to get there.
Polonius takes Hamlet aside to speak to him; Hamlet keeps up his madman act, and when his two friends arrive, although he greets them cheerfully, soon realizes that they are acting as spies for his mother and uncle. He is angry about this and feigns a general disillusionment with people and the world in general. Rosencrantz and Guildenstern tell him that they have brought a traveling acting troop with them to Elsinore. Hamlet is cheered by this, welcoming the actors and summarily dismissing his friends. He asks the actors to deliver a soliloquy about the death of Queen Hecuba and King Priam at the end of the Trojan War. Their performance gives him an idea; he will stage The Murder of Gonzago which is a play about a death very similar to his father's, and will use Claudius' reaction to it as a barometer of his guilt or innocence.
Polonius discovers that Ophelia ha in her possession love letters and tokens given to her by Hamlet; he forces her to return them; Claudius and Polonius watch for Hamlet's reaction. Hamlet is clearly distressed; is this real? Or is it an act? It is difficult to tell, but Claudius discerns from his reaction that he is not mad from love at all. It is not long before the court assembles again to watch the travelling players perform the play commissioned by Hamlet. When the Player King is murdered, poison poured in his ear, Claudius suddenlty gets up and leaves the room quickly, which Hamlet sees as proof of his guilt.
Gertrude is angry. She demands to know from Hamlet what is going on and the meeting becomes very heated. Polonnius is watching from behind a tapestry and is concerned enough for Gertrude's safety that he calls for help. Gertrude is also convinced that Hamlet is so angry that he wants to kill her and has called for help herself. Polonius rushes to Gertrude's aid but in the scuffle he is killed by Hamlet, mistakenly, because the prince believes him to be Claudius whom he had passed in the hallway on the way to speak to his mother. He tells his mother that she is foolish for being unable to see Claudius for who he really is and for never realizing that he had murdered her husband. The ghost of his father comes into his room and berates Hamlet for his brutality. Gertrude cannot see the ghost; all she sees is Hamlet arguing with himself, further proof of his insanity. Hamlet entreats her to refuse to sleep with Claudius.
Ophelia has become demented by grief because of her father's death. When Laertes arrives home from France, he is filled with rage because of his father's murder and his sister's insanity. Claudius tells him that there is only one person responsible - Hamlet. Claudius suggests a duel between Laertes and Hamlet, giving Laertes a sword with a poisoned tip. If he wins, the poison will kill Hamlet. If their plan fails, and Hamlet wins the duel, Laertes will be a gracious loser; he will offer a goblet of victory wine to Hamlet; the wine will have poison in it. Before the men can continue planning Hamlet's death, Gertrude enters the room to tell them that Ophelia's body has been found in the lake, but nobody knows if it was an accident, or if she killed herself in her madness.
Hamlet arrives as gravediggers are preparing a grave for Ophelia's body. They unearth the skull of a court jester whom Hamlet remembers from his youth. Hamlet picks up the skull, and addresses it solemnly. Ophelia's funeral procession advances, lead by Laertes, and initially Hamlet and Horatio hide, because they don't know who the procession is for; however, when Hamlet realizes it is Ophelia's funeral, he comes out from his hiding place and announces his love for her. He and Hamlet fight but their brawl is broken up quickly.
Back at the castle, Hamlet tells Horatio that whilst he was in England, he looked through the belongings of Rosencrantz and Guildnstern and found a letter to the king of England from Claudius demanding his execution. He replaced the letter, forging another that demanded Rosencrantz and Guildenstern's deaths instead. Their conversation is interrupted by a courtier who brings the duel challenge to Hamlet. Horatio does not like the idea and tries to persuade Hamlet to turn it down but the prince accepts.
He acquits himself well at the start of the duel. He leads the match, and Gertrude toasts him with pride, but she drinks from the goblet of poisoned wine and dies. Laertes knows that this will reveal the plot and he slashes Hamlet instead of fighting correctly. There is a skirmish and they both drop their weapons, then in error pick up the sword belonging to the other. Laertes is wounded by his own poisoned sword. As he lays dying, Laertes makes his peace with Hamlet and tells him that the entire plan was Claudius'. Hamlet charges towards Claudius and kills him.
Hamlet hears that Prince Fortinbras is leading his troops through Elsinore en route to Poland Knowing that he is soon to die because of the poison on the sword, he names the Norwegian prince as the successor to the Danish throne. He dies in Horatio's arms. When Fortinbras arrives at the castle and realizes that all of the Danish royal family is dead, he takes the throne, and orders a state funeral for Hamlet, as a mark of honor and respect.
