In Edinburgh, 1886, two brutal murders and a bizarre exhumation have the entire city on edge. Carus Groves, a conceited and prejudiced police inspector, is assigned the case. Baffled by the superhuman strength required to rip two men apart and drag up a coffin, Groves focuses on an anguished young woman, Evelyn Todd, who claims to have dreamed of the crimes in great detail. Meanwhile, two unlikely friends - Thomas McKnight, a jaded Professor of Logic and Metaphysics, and Joseph Canavan, a compassionate cemetery attendant - are similarly drawn towards Evelyn and her tormented psyche. They discover her extraordinary imagination was violently suppressed in childhood, but in her dreams she retains the image of the lamplighter who brightened the street outside her orphanage each evening. Evelyn now insists the killer is this lamplighter. And as a strange beast gallops through Edinburgh's misty alleys, and Groves' investigation flounders, McKnight and Canavan use the only weapons they possess - reason, logic, intuition, philosophy and sheer luck - to unearth the secrets buried in the dark recesses of Evelyn's mind!