One of the major issues critics discuss with respect to William Shakespeare's play Hamlet is why it takes so long for Hamlet to finally get around to killing Claudius. In a sense, the entire plot of the play can be described as a trajectory from Hamlet's realization that he should kill Claudius in the first act to his actually killing him at the end of the play.
Claudius is the brother of Hamlet's father, the King of Denmark, and thus Hamlet's uncle. Ambitious for power, Claudius kills Hamlet's father and marries Hamlet's mother, Gertrude, before the play begins. In the first act, Hamlet encounters his father's ghost, who tells Hamlet of the murder and commands Hamlet to avenge his death by killing Claudius. Hamlet wants to be fully convinced of Claudius' guilt, and therefore arranges a "play within a play", in which a group of traveling players re-enact his father's death in fictional form, hoping that Claudius will reveal his guilt, saying:
The play's the thing.
Wherein I'll catch the conscience of the king.
Next, Hamlet is sent to England, accompanied by messengers carrying a letter written by Claudius asking the English king to kill Hamlet. Hamlet foils the plot, but this stiffens his resolve to kill Claudius.
In the final scene of the play, Claudius poisons Hamlet's drink, but Gertrude drinks it by mistake and dies. Laertes stabs Hamlet with a poisoned sword and Hamlet also stabs Laertes with the poisoned sword. Hamlet forces Claudius to drink poison. Hamlet, Laertes, and Claudius die.