Claudius and Polonius use Ophelia for their own ends.
Characters: 
Claudius

The king takes part in Polonius’s scheme, spying on Hamlet while Ophelia speaks with him.

Gertrude

Rosencrantz and Guildenstern deliver their report to the queen, who hopes that Ophelia is the cause of Hamlet’s behavior.

Polonius

Ophelia’s father decides to send her to speak with Hamlet while he and Claudius spy.

Ophelia

Ophelia is sent to speak with Hamlet, but when she questions him, he verbally assaults her.

Rosencrantz

Hamlet’s childhood friend. He has had no luck discovering the cause of Hamlet's “madness.”

Guildenstern

Hamlet’s childhood friend. He has had no luck discovering the cause of Hamlet's “madness.”

Hamlet

The prince ruminates on life and death while being spied on by Claudius and Polonius in his most famous soliloquy. Once Ophelia enters, he viciously insults her.

Scene Summary: 

Rosencrantz and Guildenstern are having no luck discovering the reason for Hamlet’s madness, so Polonius decides to make good on his plan from Act II, Scene 2. He’ll send Ophelia to talk to the prince, while he and Claudius will watch in secret. When they withdraw, Hamlet enters alone on stage and delivers his famous “To be or not to be” soliloquy. He ponders the nature of death, realizing that while it might seem easier to leave the world behind, death is a great unknown. It’s probably best to just face the troubles you do know, rather than face the uncertainty of the afterlife. Ophelia enters and the two begin a very strained conversation. Hamlet insults her virtue and tells her that, while he may have loved her once, he certainly doesn’t love her now. After Hamlet departs, Claudius and Polonius reenter, newly suspicious that Hamlet’s madness isn’t lovesickness after all. Polonius hatches a new plan: he’ll make sure Hamlet and his mother have some alone time after the play, and he’ll spy on them to see if Gertrude can figure out what’s bothering Hamlet once and for all. If that doesn’t work, they’ll ship him off to England, where his crazy act can do no harm.