When Luther was summoned to the Reichstag (diet) of Worms, his sovereign prince obtained from the Emperor free passage for him. The man knew why he was doing this. At this diet the Emperor, as expected, imposed the Ban of the Empire upon Luther. Thus he was oulawed, and everybody was free to kill him whenever they got hold of him. This way Church and Emperor hoped to get rid of him once and for all.
And, as fate demanded, on his journey home Luther was attacked by a mob of highwaymen, as it seemed, and abducted to Wartburg Castle.
Frederick the Wise, Elector of Saxony, found himself in a difficult situation. Being a subject to his emperor he certainly could not officially an outlaw, on the other side however, he was prepared to patronize his ablest theologian. So he ordered his own men to obduct Luther, lest anybody else was doing this.
And yes, this is a mini version of Wartburg Castle.
(Pics = links)