In Act One, Claudius finds Ros and Guil and tells them that Hamlet seems transformed ever since his father's death. He asks them to cheer him up and to find out what is wrong with him.
In Act Two, he tells them that they should work harder to figure out what Hamlet is up to, and plots to have Hamlet run into Ophelia accidentally.
After Hamlet tells Ophelia to go to a nunnery, Claudius appears and says that Hamlet is not mad and that he is not in love with Ophelia. He thinks Hamlet could be dangerous and plots to send him to England.
Claudius announces that Hamlet has slain Polonius, and asks Ros and Guil to find him and bring Polonius's body to the chapel. The next time he sees them, he asks them to bring Hamlet before him.
In Act Three, Claudius's body appears at the end, along with Gertrude's, Hamlet's, and Laertes. He is ultimately slain by Hamlet.