The Dream Killer of Paris by Fabrice Bourland

London 1934 and the detective partnership of the cerebral Andrew Singleton and the muscular James Trelawney find themselves without a case to investigate.   Singleton decides to use his free time to go to Paris as he is obsessed by the death, at the time designated as suicide, of the nineteenth century poet Gerard de Neval.   Relaxing on the deck of the cross channel ferry he first sees a mirage of a castle in a wooded valley and encounters a young lady who may not actually exist.   In Paris he is contacted by an old friend, Superintendant Fourier of the Surete, who asks him to assist with the investigation into the mysterious death of the Marquis de Brindillac.   Bourland proceeds to spin a fantastical tale with many elements of the supernatural which may not be to everyones taste but which I found vastly entertaining.   The translation from the French is by Morag Young.