The lady doth protest too much Introduction
I'm Gertrude. I'm Hamlet's mom and Queen of Denmark. When my husband died, I married his brother, which really upset my son. And you know what I think?
Madam, how like you this play?
The lady doth protest too much, methinks.
O, but she'll keep her word. (3.2.239-241)
Who Said It and Where
A ghost appeared to Hamlet and told him that his uncle Claudius murdered his father. He's not sure whether he can believe the ghost or not. He thinks he can trust the creepy crawler since he just happens to be his dear old dad. But then again: should he really take his tips from dead apparitions roaming the castle at night?
Things are looking up when some players (actors) come into town. Hamlet commissions them to perform a play. But this isn't just any play. In it, a king is murdered in the same way Claudius murdered Hamlet's father. Hamlet plans to watch Claudius's reaction to see if the ghost is telling the truth. The play is called The Mouse-Trap since it will (hopefully) trap Claudius.
As everyone gets settled to watch the play, Hamlet pulls his buddy Horatio aside and tells him how great he is. Oh, and by the way, he needs a favor: he wants Horatio to watch Claudius' reactions to the play, especially during the scene that reenacts the killing of the King.
Then Hamlet goes back to the group of people ready to watch the play. After brutalizing Claudius with some weird and awkward banter, Hamlet moves on to Polonius and Ophelia. He starts flirting with—well, really harassing—Ophelia by making a bunch of dirty jokes and Elizabethan euphemisms.
Anyway, Ophelia tactfully demurs, telling Hamlet it's nice to see him so happy. Hamlet quips that there's no way he could be unhappy. After all, his dad's only been dead two hours, and his mom already seems quite happy. Ophelia points out that, actually, his "two hours" is more like months. He responds that it's amazing how a great man can die and not be forgotten in two months' time.
Now it's really time for the show to begin.
In the first scene, the Queen repeatedly swears to her husband (the King) that she will never remarry. Oh, sure, says the King in the play: she's faithful now, but she'll forget all her faithfulness as soon as she's in her new husband's bed, which should happen roughly about the time her old husband dies.
This is obviously offensive to Gertrude, but she still keeps her cool. When Hamlet asks her how she likes the play, she responds, "The lady doth protest too much, methinks." Hamlet says the play is a wicked piece of work, but wouldn't bother anybody with a clean conscience. Burn.
Here come the fireworks. The husband/King is taking a nap when his brother sneaks in and pours poison in his ear, which is exactly what Claudius did to Hamlet's father. Seeing this, King Claudius gets out of his seat and rushes out of the room. Sold! Hamlet has proved Claudius's guilt—to himself, at least.
As everyone but Hamlet and Horatio rushes out of the room, Hamlet gloats about this brilliant performance. But in come Rosencrantz and Guildenstern, with the message that Gertrude is upset about the play and wants to talk to her son. Uh-oh.