A ghost resembling the late King of Denmark appears on the battlements of Elsinore, witnessed by the night watch of Bernardo, Marcellus, and Horatio, who resolve to tell Prince Hamlet. Claudius dispatches envoys to Norway, grants Laertes permission to return to France, admonishes Hamlet for lingering grief and orders him to remain in Denmark; Hamlet delivers a bitter soliloquy lamenting his mother’s swift remarriage and the state of the world, then learns from Horatio, Marcellus, and Bernardo about the ghost of his father and vows to keep watch that night. Laertes prepares to leave for France, urging Ophelia to distrust Hamlet’s romantic overtures as politically dangerous; Polonius delivers his famous counsel to Laertes and warns Ophelia that Hamlet’s promises are unreliable and should be avoided. Hamlet, Horatio, and Marcellus meet the Ghost on the castle platform; Hamlet, defiant, insists on following the specter despite their protests, and the Ghost leaves the scene with him, prompting Marcellus to remark that something is rotten in the state of Denmark. The Ghost reveals that King Hamlet was poisoned by his brother Claudius, commands Hamlet to avenge his death while sparing his mother, and Hamlet vows to feign madness and swears Horatio and Marcellus to secrecy. Polonius dispatches his servant Reynaldo to spy on Laertes in France; Ophelia tells Polonius that Hamlet behaved erratically after their encounter, prompting Polonius to conclude Hamlet is lovesick; Polonius reports this to King Claudius and Queen Gertrude, who decide to enlist Hamlet’s school friends Rosencrantz and Guildenstern to discover the cause of his madness; Hamlet meets Rosencrantz and Guildenstern, who reveal they were sent by the King and Queen; later a troupe of actors arrives, and Hamlet, thrilled by a speech about a king’s murder, vows to use their play to expose Claudius’s guilt. Polonius instructs Reynaldo to spy on his son Laertes in France, and Ophelia reports Hamlet’s disheveled, frantic behavior to Polonius, leading him to conclude Hamlet’s madness is love‑driven and to resolve to inform King Claudius. Claudius commissions Rosencrantz and Guildenstern to discover the cause of Hamlet’s odd behaviour; Polonius reports to the court that Hamlet’s madness may stem from Ophelia’s affection and his father’s death, and proposes to place Ophelia near Hamlet to observe him; Norwegian ambassadors Voltimand and Cornelius deliver news of peace with Fortinbras and a royal tribute of three thousand crowns; Hamlet meets the returning friends, mocks Polonius, delivers his “What a piece of work is a man” soliloquy, and decides to stage a play reenacting his father’s murder to catch the king’s conscience.