Hamlet is a "revenge tragedy," in which Hamlet seeks vengeance against his father's murderer, his uncle Claudius, the king of Denmark. Much of its fascination lies in its uncertainties. What is the Ghost--Hamlet's father demanding justice, a tempting demon, an angelic messenger? Does Hamlet go mad, or merely pretend to? Claudius is a murderer, why does he not act? Was his mother unfaithful to her husband or complicit in his murder?