Caitlin and Cal are two ordinary kids who embark on a routine errand that turns out to be the adventure of a lifetime.
Caitlin is a typical twelve-year-old girl; well, typical for a girl who is being brought up by her single mother, Ethelinda, in the superstitious twelfth century. Caitlin lives in the village of Badgerbank, helping her mother by gathering plants and other ingredients that Ethelinda needs for her healing potions.
Caitlin's got the same problems as any girl her age: a smart-alec brother, Cal, who gets under her feet; a mother who expects her to grow up too quickly; and an absent father who has passed on a few gifts to Caitlin that she doesn't even realise she possesses.
When Lady Mallory becomes desperately ill, Ethelinda is called to tend her. She sends her two children on a quest for some Devil's Ear, a fungus that will help save her patient's life. But what should have been a fairly routine trip turns out to be a journey of thrills, fear and discovery for Caitlin and Cal as they encounter a world of extraordinary events and characters (and they're just the ones who can speak . . .).