What plan do the men make? What does Rudolf need to do to make it work?

When the men hear that the king is quite sick, they decide to break into the castle and rescue him. Here is the plan:
Johann opens the front door to the new castle at 2:00 in the morning. Sapt and his men run into the castle and hold the men who are sleeping there. When Duke Michael hears Antoinette’s cry for help and runs out of his room, Sapt will catch him and take the key from him. Sapt lets down the drawbridge. When Rupert and De Gautet hear the noise and cross the drawbridge, Rudolf will kill them. In order to do that, Rudolf needs to hide himself in the river by the bridge and wait for them to pass the bridge. Then Rudolf, Sapt, and their men rush to the king’s room and kill Detchard and Bersonin before they have time to kill the king.