Welcome to Camberwick College, a less than prestigious finishing school for magical dunces.
Since his mysterious death in 1874, Dean Castigus Camberwick's timekeeping has been spotty at best and thus he has done a dashedly awful job of maintaining discipline at his namesake college built upon the Blighted Ravine, leading to a perilous climate where all manner of humiliations and indignities may befall the faculty and their wards.
As everyone knows, all magical mammalians are required upon their nineteenth birthday to have gained merit in at least one field of witchery or wizardry, at which point they are assigned their lifelong career based on merit. Institutions such as Castigus's college exist as a last ditch attempt to save flunkees such as Briony Gardner and Jilly Beesley from the eternal shame of being forever cast out into the ugly, mundane, and downright tedious human world.
They must remain in college for the full duration of their temporal loop-year no matter the challenges they face!!
Mind control, disappearing clothes, magical binding, enchantments, curses, ghouls, apparitions, wicked wizards, wanton witches, and all manner of tendrils and tentacles await those mature students unwitting or unskilled enough to find themselves enrolled at Camberwick College.