Calla North and her mum Elizabeth live a life that’s far from normal. There are days when the power is cut off and Calla has to do her homework by candlelight; there are others when curious strangers want to talk to Elizabeth about her research on ducks. When Elizabeth says yes to a once-in-a-lifetime trip to save a small brown duck, she sends Calla to the best place she knows: The School of the Good Sisters. Staffed by nuns whose preferred subjects include light aircraft maintenance, camouflage skills, and cake – lots of cake – Calla is about to discover her bravery, and to learn that when trouble comes, there’s no better back-up than a Blessing of Nuns.