Hamlet is a play by William Shakespeare about a young prince named Hamlet that has lost his father, King Hamlet Sr., to unknown causes- whether it be murder by Claudius (Hamlet's uncle and also brother of Hamlet Sr.) or simply old age. The play takes place in the lovely Denmark. Hamlet's father haunts him as a ghost and that's when Hamlet realizes/decides that Claudius indeed did kill his father. Whether or not Claudius killed Hamlet Sr. is unknown, but Hamlet had no doubt in his mind that it was him. From then on, Hamlet goes on to plot his revenge on his uncle who is now the new king and husband of his mother, Gertrude. His mind wanders as he finds a way to get rid of his uncle and uncover the truth about his father's death. On this journey he seems, and is said to be mad by the characters.

This "madness" didn't take off until Claudius took the crown. Also, with the marriage between his mother and Claudius, he seemed to be even more so upset. Hamlet shows throughout the play odd behaviors towards his mother, you could even say he could have been in love with his mother. Unfortunately, Shakespeare is no longer with us, so we won't really ever know what was going on in that odd relationship. Hamlet finds any possible way to rid of his uncle, but it prolongs due to his inability to make decisions. 

Hamlet puts on a play, "Murder of Gonzago", which is about what he believes Claudius did to King Hamlet Sr.. He introduces this play to the characters to see Claudius' reaction and to let him know that Hamlet knows what he did. The new King reacts and Hamlet believes its proof that he did commit the crime and he must pay. Now, Claudius believes that Hamlet wants to kill him which was true.

Then, Ophelia, Hamlet's supposed "lover" literally goes insane with grief and commits suicide by drowning herself when Hamlet kills her father, Polonius, for spying on him and his mother's conversation (in his defense, he did think it was Claudius spying and could not see Polonius). Laertes, Ophelia's brother, decides to get revenge on Hamlet for the death of both his father and innocent sister. That's when the play gets crazy.

Laertes and Claudius team up and decide to kill Hamlet with poison. They come up with two plans, the first being a sword Laertes uses to fight Hamlet that has poison on it; the second being a cup full of poison in case Hamlet were to win the duel between Laertes and Hamlet. The cup of poison would serve as a celebratory drink for Hamlet. Everyone gets together and watches Laertes and Hamlet fight. Hamlet gets poisoned by Laertes' sword and Laertes is poisoned by his own sword. Gertrude drinks out of the poisoned cup, and then as Hamlet sees his mother die, Laertes fesses up about the poison and Hamlet stabs Claudius with the poisoned sword. 

In the end, almost all important characters die. After this very long feud between this family, there is no blood relative of Hamlet's remaining, leaving Fortinbras, prince of Norway, who always wanted to avenge his father since Hamlet's father killed him, becoming the new king. All craziness ends there.