Frances and Louisa, the doctor's daughters, are used to having to deliver medicines over the moors. One day they're asked to take heart medication to Mrs Hathaway. She's joined Dr Burnett's practice after her previous one decided she was hearing things when she reported hearing intruders in her house at night.

Could Mrs Hathaway be telling the truth? Could those strange noises at night be people breaking in, over and over again?

Frances, Louisa and their friends decide to stay in her stables overnight and see.

It'll give Frances the chance to see what Orlando, the horse she has on trial, is like. He's prone to spectacular bucks and alarming cavorting, but could he be the horse to replace Frances' beloved Redwing? Perhaps their journeys over the moor to help Mrs Hathaway will help Frances find her new horse.