Miss Blaine's Prefect and the weird sisters
(Book)

"Shona McMonagle is your ordinary, garden-variety librarian: comfortably padded, in her middle years, expert in various arcane martial arts. She also has an impressive knack for time travel ("impressive" may be overstating things: her first two forays - revolutionary Russia, 19th-century France - went less than smoothly). Her latest mission? Head to 11th-century Scotland, cozy up to Macbeth and Lady M, prevent them from murdering Duncan. In the ordinary course of things, this would be a doddle. But then there are the witches, who prove remarkably quick to take offense. And the business of being turned into a mouse. And the fact that the mission is in truth threefold. One, keep Duncan alive and kicking; two, correct the historical record and lay bare the ludicrous lies introduced by that silly Shakespeare play; and three, burnish the honor of the Marcia Blaine School for Girls, the finest institution of pedagogy in the greater Edinburgh area. Can she do it?"--,Dust jacket flap.