Brian Roberts
Sergeant Brian Roberts is a very unhappy guard with multiple loyalties. Not only has he been ordered, by a newly-arrived duchess who doesn't know how things work around here, to imprison a witch, he has the too-clever-for-his-own-good junior guard Preston to deal with, as well as the new Baron and his wife. And her mother.
Annotation
Note the resemblance to the plot of Wyrd Sisters at this point in I Shall Wear Midnight, as well as to the "Swamp Castle" scenes in "Monty Python and the Holy Grail"...