Francisco and Bernardo, two guards of Elsinore Castle invite Horatio the scholar and his guard Marcellus over to the castle to see if they have any ideas about a strange thing that they have seen...a GHOST that looks just like their dead King! Horatio tries to make the ghost speak, but it is silent. They need the King's son, Hamlet...
Hamlet is at his Uncle's coronation where his mother (Claudius' wife) and Claudius want him to stop grieving for his Father and get on with celebrating the new king and 'Father' that Claudius supposedly is.
Hamlet is there and the Ghost explains that Hamlet's Uncle, Claudius, the new King, murdered Hamlet's Father, the old King and married his wife! ALL whilst pretending that the old king was bitten by a snake! Hamlet may now go insane.
Ophelia, Hamlet's lover, is saying goodbye to her brother Laertes before he leaves to continue his studies in France. Laertes and Ophelia's Father both believe that Hamlet does not truly love Ophelia, it is just a phase (which Ophelia denies).