"O, from this time forth, my thoughts be bloody, or be nothing worth"
King Claudius realized Hamlet's plan to kill him and tried to send Hamlet off to England to be killed. This plan failed and Hamlet is left reflecting over how much time he's wasted in killing the king. As Prince Fortinbras' army approaches Denmark in an attempt to attack and win the land, Prince Hamlet finds his resolve, deciding he will waste no more time in killing the king.
As Hamlet returns to the castle, he is met with Laertes, Polonius' son, who challenges Hamlet to a duel to avenge his father. Hamlet agrees, not knowing that Laertes' sword tip is poisoned. The king also poisoned Hamlet's drink should he get thirsty during the duel in an attempt to kill him.
During their duel, Hamlet and Laertes both got hit with the poisoned sword, Laertes succumbing to death first. Meanwhile, an unsuspecting Queen Gertrude drank the poison intended for Hamlet and ultimately died of the poisoning. Before Hamlet himself died, he was able to finally avenge his father and killed the king by feeding him his own poison. After everyone lay dead on the floor, Horatio was left to tell the story just as Fortinbras and his army arrived and took over Denmark.