What is the significance of "The Mousetrap" in Hamlet regarding suspense, appearance vs. reality, and the overall effect on the plot and characters?
In Shakespeare's Hamlet, the play-within-the-play, which Hamlet tells Claudius is titled, The Mousetrap, creates suspense by providing a way for Hamlet to know if the Ghost is telling the truth about King Hamlet's death. Thus, as Hamlet waits to see Claudius's reaction, so does the audience. That's suspense.
Throughout the play, virtually no one in the play is what they seem, or more specifically, no one is playing the role that is expected (Hamlet acts insane, Ophelia, Rosencrantz, Guildenstern, Polonius, and Claudius all act as spies, etc.). Hamlet himself raises the issue of seeming when he insists that others may only seem to be in mourning, but he genuinely is in mourning. Continuing this theme, The Mousetrap seems to be only a simple entertainment, but in reality is a trap. And Claudius seems to be innocent to the people of Denmark, but is not. The Mousetrap is Hamlet's means of exposing the truth--at least to himself.
The play, and Claudius's guilty reaction to it, give Hamlet corroboration for the Ghost's story. This frees Hamlet to morally kill Claudius. It also sends Claudius into a figurative tailspin, moving him to an emotional prayer. The play should conclude when Hamlet finds Claudius at prayer and has a chance to kill him. It doesn't, however, because Hamlet doesn't want to send Claudius to heaven by killing him as he confesses. And this leads to the climax of the play.
Hamlet goes beyond his station in life when he attempts to determine another human being's eternal salvation. When he doesn't kill Claudius he is guilty of hubris (acting above one's station in life), and he dooms himself and numerous others.
Thus, The Mousetrap leads directly to the climax. And though Hamlet's plan works--the mouse is trapped--and Hamlet wins the cat-and-mouse game he's been playing with Claudius, the play-within-the-play also leads to the climax and Hamlet's doom.
"The Mousetrap" also affords Shakespeare the opportunity to drive home one of his favorite themes, a theme that runs through many of his plays -- "All the world's a stage/And all the men and women merely players" (As You Like It). A Midsummer Night's Dream is the other work in which there is an actual play-within-a-play (unless you count the Induction of The Taming of the Shrew, which makes the main plot of that play a play-within-a-play). "All the world's a stage" was one of Shakespeare's favorite ways to examine the theme of appearance versus reality.
There are many other references in his plays as to how, for Shakespeare, the world of the theater and the "real" world are interchangeable, but here, in Hamlet, he devotes quite a bit of time to the players and their effect on Hamlet and Claudius.
"The Mousetrap" is designed to, through appearance, do what, in reality, Hamlet cannot, "catch" the King. He has a beautiful soliloquy, after the entrance of the players about how the actor is able to become so committed to his character that he can cry fake tears, but that he, Hamlet, with a real task before him, cannot move a muscle. So, he decides to follow the actor's theatrical lead and "catch the conscience" of the king through artifice rather than direct "real life" confrontation.
It works, much to his delight. However, the irony is that, once Claudius has called for "Light" and the play is over, Hamlet is right back in the real world where he started, unable to act.
By reenacting the actual events that led to old Hamlet's death, as told to him by the ghost with an already popular play, "The Murder of Gonzago", Hamlet hope to trap Claudius.
Since Horitio is the only person Hamlet trusts, he charges his friend to watch the king's reaction to the play. It is not that he doesn't trust his own eyes but a second opinion, as it were, would help.
Of course, when Claudius suddenly stops the play and calls for lights, he tips his hand. Hamlet has the verification that he had been looking for and feels that he can now proceed.
"The Mousetrap" is critical for Hamlet. Through it, he gets the information he is looking for.
During "The Mousetrap" Shakespeare has two plays going at once. The outer play which has an animated Hamlet doing his best to hold in his excitement and the inner play of clueless actors. The inner play containing its own tensions, is the impetus for much of the tension in the outer play. From earlier in this scene Hamlet expressed his dislike of Dumb-shows. And yet the players open the Mousetrap with a dumb-show that threatens to spring the trap. After the dumb-show we are left with the question of whether the king did or didn’t note the “argument of the play.”
Aside from the dumb show the inner play is really two plays in one. The first we might properly call “The Mousetrap”. Observe later in Gertrude’s closet where Hamlet suggests the pet name of “mouse” for Gertrude. The Mousetrap’s focus is on Gertrude. The bearing of souls between the Player Queen and the Player King is Hamlet’s attempt to catch the conscience of Gertrude. Did she have any hand at all in the plotting and killing of King Hamlet? All we get from Gertrude is that the lady protests too much.
On to scene two the “Murder of Gonzago”. This is directed at Claudius and where both Shakespeare and Hamlet ratchet up the tensions. Hamlet’s earlier admonishment that the players will “tell all” would be better observed by Hamlet at this point. Hamlet is the one who should guard his words. As Ophelia tells him, “You are as good as a chorus....” Hamlet’s first slip “poison in jest,” unduly calls attention to the dumb-show poisoning. His next slip is identifying Lucianus as “nephew to the king.” It is not pertinent to the story but it does make Claudius and others aware of a parallel between Hamlet and Lucianus. So when Claudius does exit the play is it his guilt, or the overt threat of a nephew killing the king that does so? Or perhaps it is seen as a tasteless prank.
The result is that Hamlet is convinced that the king is guilty. This brings about the death of Polonius and sets in motion the Laertes revenge subplot. As for Claudius, he sees Hamlet as a danger and doubles his efforts to be rid of him.