Blind detective Duncan Maclain gets mixed up with enemy agents and murder when he tries to help an old friend with a rebellious stepdaughter.

Set in 19th-century New York, this mystery begins when a Frenchwoman shows up at the home of one of Napoleon's former marshals. The alcoholic man is badly crippled and slowly dying, but this doesn't stop the forthright lady from pushing him to change his will to include his estranged grandson so that he can help out the struggling French Republic. Unfortunately, the dying man's conniving housekeeper and butler, already planning murder to get the money themselves, overhear her and begin plotting her demise.

A wealthy invalid tries to add his hard-working cook to his will, but the conniving butler gets in the way.