The Prisoner in the Mask — Dennis Wheatley

Why would a French aristocrat renounce his country and live in exile? The answer lies in the Paris of the 1890s; a world of superficial glamour but, under the surface, deep social and political strife. The army, discredited by the Dreyfus case, was being purged. The young de Richleau, cadet and then instructor at the military academy of St. Cyr, became involved in a conspiracy - to restore the French monarchy - with the Duc de Vendome being secretly coached in his future role of King.

What happens if the conspiracy is betrayed? For some: death. For de Richleau, the life of a fugitive who has declared a single-handed vendetta against the government.