After the arrival of monstrous Aunt Mary, much of Cockermouth falls ill with a mysterious stomach bug. On a hunch from one of their aunt's crazy drawings, telepathic sisters Mae and Isla Donaldson follow a trail of ambition and despair that leads to the door of a famous family, exposing the darkness within. Is this one secret too many? Meet the Donaldson girls - primary schoolers and detectives. Mae, clever and very, very proper. Isla, a wild, artistic soul most at home wandering the fells of England's beautiful Lake District. They are united by an uncanny ability to share their thoughts.