October, 1460 in the Lothians of Scotland. When the monks of Cambusdonald Abbey are told they must put on a show to impress a possible benefactor, Brither Barnabus, the abbey's alchemist, digs out an ancient book of spells. But the monks get more than they bargained for when their spells start to go wrong, filling the monastery with unwilling (and some only too willing) visitors. Things get worse when the formidable Inspector General of the Order arrives. Mayhem ensues with hilarious results.