In Shakespeare's Hamlet, Rosencrantz and Guildenstern likely do not know the contents of the letter that King Claudius sends with them to England, but they are still guilty of going along with the king's plot to get Hamlet out of Denmark.

Claudius and Gertrude call Rosencrantz and Guildenstern, school friends of Hamlet, to come to Denmark and see if they can figure out what is going on with the prince. Hamlet seems to have gone crazy after his father's death, and he needs to be watched. Rosencrantz and Guildenstern appear to be just the two to do that. Hamlet is not, of course, actually crazy. He is putting on an act so that he can figure out for sure if his father was really murdered and, if so, what to do about it.

Claudius then determines to send Hamlet to England along with Rosencrantz and Guildenstern. He gives the pair a sealed letter with instructions. Claudius tells them that the trip is due to Hamlet being so crazy that it isn't safe to keep him around any longer. But really, Claudius sends a message to the English king with the request that the latter put Hamlet to death.

Rosencrantz and Guildenstern do not know this. They think that Hamlet is being banished for his madness and also for killing Polonius. They do not open the sealed letter. But Hamlet does—very carefully so that no one will notice the tampering. He is surprised at what he reads, and he composes a new letter to replace the original, sealing with his father's State Seal. The new orders tell the English king to execute Rosencrantz and Guildenstern. Hamlet escapes.

Do Rosencrantz and Guildenstern deserve their fate? They probably do not, especially if they really do not know the contents of the letter. Hamlet assumes they are in on the plot, but they are merely acting out of loyalty to the king rather than deliberately betraying Hamlet.