As we know, there is a mysterious teleportation pad near Stonegate. It takes you to Lord British’s Castle, in front of the throne room, to be exact. Nobody tells you who set it up, and so we are left wondering how it comes that such a powerful teleportation device was built in the wilderness.
However, the sheer existence of that strange teleportation pad explains why there are so many people missing in Lord British’s Castle:
Giant Rats and wolves accidentally stepped onto the pad and appeared in Castle British!
One of those Giant Rats not only devoured Nystul, but also good old Chuckles and Sherry the mouse. (Which explains why there aren’t even graves for them.) Lord British, deeply shocked by the meaningless death of his friends, prohibited sleeping in his castle, ordered his knights to be on guard 24 hours a day, and had all weapons locked up in unbreakable showcases.
(The most elderly king, by the way, already was a little absent-minded, and he didn’t realize that a Giant Rat killed Nystul and Chuckles; Instead, he thought the beast was merely a wild-gone horse, so he had all horses in the entire kingdom hung in one of our darkest hours as a people.)