Who are Rosencrantz and Guildenstern and why have they been invited to the castle?

Rosencrantz and Guildenstern are characters from William Shakespeare's play "Hamlet." They are childhood friends of Prince Hamlet and are summoned to the Danish court by King Claudius and Queen Gertrude to spy on Hamlet and uncover the cause of his apparent madness. Their loyalty is tested as they navigate their roles between friendship and duty, ultimately succumbing to the manipulation of the royal court. Their presence highlights themes of betrayal and the complexities of human relationships within the play.