Prince Hamlet is depressed. Having been summoned home to Denmark from school in Germany to attend his father's funeral, he is shocked to find his mother Gertrudealready remarried. The Queen has wed Hamlet's Uncle Claudius, the dead king's brother. To Hamlet, the marriage is "foul incest." Worse still, Claudius has had himself crowned King despite the fact that Hamlet was his father's heir to the throne. Hamlet suspects foul play.
When his father's ghost visits the castle, Hamlet's suspicions are confirmed. The Ghost complains that he is unable to rest in peace because he was murdered. Claudius, says the Ghost, poured poison in King Hamlet's ear while the old king napped. Unable to confess and find salvation, King Hamlet is now consigned, for a time, to spend his days in Purgatory and walk the earth by night. He entreats Hamlet to avenge his death, but to spare Gertrude, to let Heaven decide her fate.
Hamlet vows to affect madness — puts "an antic disposition on" — to wear a mask that will enable him to observe the interactions in the castle, but finds himself more confused than ever. In his persistent confusion, he questions the Ghost's trustworthiness. What if the Ghost is not a true spirit, but rather an agent of the devil sent to tempt him? What if killing Claudius results in Hamlet's having to relive his memories for all eternity? Hamlet agonizes over what he perceives as his cowardice because he cannot stop himself from thinking. Words immobilize Hamlet, but the world he lives in prizes action.
In order to test the Ghost's sincerity, Hamlet enlists the help of a troupe of players who perform a play called The Murder of Gonzago to which Hamlet has added scenes that recreate the murder the Ghost described. Hamlet calls the revised play The Mousetrap,and the ploy proves a success. As Hamlet had hoped, Claudius' reaction to the staged murder reveals the King to be conscience-stricken. Claudius leaves the room because he cannot breathe, and his vision is dimmed for want of light. Convinced now that Claudius is a villain, Hamlet resolves to kill him. But, as Hamlet observes, "conscience doth make cowards of us all."
In his continued reluctance to dispatch Claudius, Hamlet actually causes six ancillary deaths. The first death belongs to Polonius, whom Hamlet stabs through a wallhanging as the old man spies on Hamlet and Gertrude in the Queen's private chamber. Claudius punishes Hamlet for Polonius' death by exiling him to England. He has brought Hamlet's school chums Rosencrantz and Guildenstern to Denmark from Germany to spy on his nephew, and now he instructs them to deliver Hamlet into the English king's hands for execution. Hamlet discovers the plot and arranges for the hanging of Rosencrantz and Guildenstern instead. Ophelia, distraught over her father's death and Hamlet's behavior, drowns while singing sad love songs bemoaning the fate of a spurned lover. Her brother, Laertes, falls next.