A Trick of the Light sees Inspector McLevy team up with Arthur Conan Doyle to pursue a ruthless killer. It is 1860 and a Confederate officer, Jonathan Sinclair, arrives in Edinburgh with a sheaf of money to purchase a blockade-runner from Clydeside shipbuilders. He is betrayed to the Union forces and is shot dead by their secret agents. Who are they and where is Sinclair's money? Meanwhile, a beautiful young American spiritualist, Sophia Adler, is the toast of upper-class Edinburgh with her dramatic seances. However, she could yet prove to be the deadliest woman McLevy and Conan Doyle will ever encounter.