Back at Elsinore, Hamlet explains to Horatio that he had discovered Claudius's letter with Rosencrantz and Guildenstern's belongings and replaced it with a forged copy indicating that his former friends should be killed instead. A foppish courtier, Osric , interrupts the conversation to deliver the fencing challenge to Hamlet. Hamlet, despite Horatio's pleas, accepts it. Hamlet does well at first, leading the match by two hits to none, and Gertrude raises a toast to him using the poisoned glass of wine Claudius had set aside for Hamlet. Claudius tries to stop her, but is too late: she drinks, and Laertes realizes the plot will be revealed. Laertes slashes Hamlet with his poisoned blade. In the ensuing scuffle, they switch weapons and Hamlet wounds Laertes with his own poisoned sword. Gertrude collapses and, claiming she has been poisoned, dies. In his dying moments, Laertes reconciles with Hamlet and reveals Claudius's plan. Hamlet rushes at Claudius and kills him. As the poison takes effect, Hamlet, hearing that Fortinbras is marching through the area, names the Norwegian prince as his successor. Horatio, distraught at the thought of being the last survivor and living whilst Hamlet does not, says he will commit suicide by drinking the dregs of Gertrude's poisoned wine, but Hamlet begs him to live on and tell his story. Hamlet dies in Horatio's arms, proclaiming "the rest is silence". Fortinbras, who was ostensibly marching towards Poland with his army, arrives at the palace, along with an English ambassador bringing news of Rosencrantz and Guildenstern's deaths. Horatio promises to recount the full story of what happened, and Fortinbras, seeing the entire Danish royal family dead, takes the crown for himself, and orders a military funeral to honor Hamlet.
The following morning, Higgins rushes to his mother, in a panic because Eliza has run away. On his tail is Eliza's father, now unhappily rich from the trust of a deceased millionaire who took to heart Higgins' recommendation that Doolittle was England's "most original moralist." Mrs. Higgins, who has been hiding Eliza upstairs all along, chides the two of them for playing with the girl's affections. When she enters, Eliza thanks Pickering for always treating her like a lady, but threatens Higgins that she will go work with his rival phonetician, Nepommuck. The outraged Higgins cannot help but start to admire her. As Eliza leaves for her father's wedding, Higgins shouts out a few errands for her to run, assuming that she will return to him at Wimpole Street. Eliza, who has a lovelorn sweetheart in Freddy, and the wherewithal to pass as a duchess, never makes it clear whether she will or not.