The Passing of Charles Lanson — Louis Tracy

A Golden Age mystery featuring Scotland Yard's formidable detective duo: Chief Superintendent Winter and Inspector Furneaux.
 
A peaceful night in the small village of Sleaford is disturbed when a local constable is attacked by a mysterious assailant. Soon thereafter, an even worse disaster strikes. Financial magnate Charles Lanson is found dead, stabbed in the library of his nearby castle.
 
Luckily, Chief Superintendent Winter of Scotland's Yard Criminal Investigation Department is on the scene, visiting Sleaford on holiday. The shocking murder of the Anglo-Greek banker, who amassed a fortune during the Great War, seems to be an inside job. Calling in Inspector Furneaux for help, the two must root out motive and means from a suspect pool that includes three private secretaries, a daughter prone to trance-like states, and an enigmatic financier. A trail of clues leads Winter and Furneaux from the quaint English countryside into the heart of an international conspiracy that puts millions of dollars -- and a kingdom -- at stake.