More detail: 2.5 minute read. Act I. Late at night, guards on the battlements of Denmark's Elsinore castle are met by Horatio, Prince Hamlet's friend from school. The guards describe a ghost they have seen that resembles Hamlet's father, the recently-deceased king. At that moment, the Ghost reappears, and the guards and Horatio decide to tell Hamlet. Claudius, Hamlet's uncle, married Hamlet's.