Fifty-something librarian Shona McMonagle is a proud former pupil of the Marcia Blaine School for Girls with a deep loathing for The Prime of Miss Jean Brodie, which she thinks gives her alma mater a bad name. After a visit from Miss Blaine herself, involving a bad-tempered exchange about Robinson Crusoe and improper book shelving, Shona is sent spinning through time and space for another mission. She finds herself on an island, with little in the way of clues to help her decipher the purpose of her trip. Despite initially wondering if this might be a rare treat from Miss Blaine, she soon realises this is no holiday. Her island is not tropical; it's in the Baltic Sea - and it's the fifteenth century. Luckily she's kitted out for all eventualities and finds her local languages are not too rusty, which is useful when she encounters pirates, Krakens and other monsters.