HamletThe prince is eager to hear from the ghost and agrees to kill Claudius according to its wishes. He decides he will do this by pretending to be mad., GhostThe mysterious figure who claims to be Hamlet’s father. He tells Hamlet he was killed by his brother, Claudius, who is now the new king, and he urges Hamlet to avenge his murder., HoratioHamlet's friend promises not to speak of the ghost to anyone., MarcellusThe Danish soldier is sworn to secrecy about the ghost by Hamlet.
The ghost tells Hamlet that he is, in fact, the ghost of his dead father. And there’s more: the ghost claims that Claudius killed him, taking his throne and his wife in the process. He wants Hamlet to kill Claudius in revenge. Shocked, Hamlet agrees and vows to avenge his father’s death. When Horatio and Marcellus reenter, having followed Hamlet to the scene of his chat with the ghost, they promise to keep quiet about what the ghost told Hamlet. Hamlet also tells them that he might start acting a little crazy because he’ll be using insanity as a cover while he investigates what’s really going on.