Sabrina neglects a vital fact in her use of incantations: if she fails to consider a spell's consequences, there will be a ruinous aftermath. When she accidentally sends her aunts and Salem to Merlin's castle where they are held captive, it's up to the Quizmaster to teach Sabrina a valuable lesson.

Mark has his doubts that the locum consultant isn't up to the job and is proved right as a young boy is injured during an fray between his father and teacher.