Hamlet, the prince of Denmark, is disturbed by his father's recent death and his mother's hasty remarriage to his uncle, Claudius (who has now assumed the throne). The ghost of Hamlet's father appears before him and confirms his worst suspicions: Claudius murdered his own brother to seize the throne. Urged on by his father's ghost, Hamlet is determined to seek revenge.
As he seeks to further investigate Claudius's guilt, Hamlet decides to feign madness to avoid arousing suspicion. Over time, however, it becomes less and less clear whether Hamlet is merely acting mad or whether his quest for revenge has actually deteriorated his sanity. He mistreats Ophelia, the woman he loves; kills Polonius, one of Claudius's loyal followers; and knowingly sends his former friends Rosencrantz and Guildenstern to their deaths. All the while, Hamlet agonizes over his inaction and seeming inability to avenge his father's death. These internal frustrations led Hamlet to frequently question the point of life and whether it's worth living at all.
Feeling threatened by Hamlet, Claudius arranges to have him killed in a duel with Laertes (Ophelia's brother and Polonius's son). Laertes, who seeks his own revenge on Hamlet, and Claudius conspire to poison Laertes's sword, meaning even a scratch will kill Hamlet. Their corrupt plan takes a turn, however, and in the course of the duel, Hamlet, Laertes, Gertrude, and the king are all killed, leaving Horatio, Hamlet's best friend, alone to tell their story.