The Lyons Mail case presents one of history's most intricate and enduring criminal mysteries. Charles Oman, a historian, delves into the complex details of this notorious crime, which involved a significant sum of money intended for General Bonaparte during his Italian campaign. The narrative navigates the involvement of prominent historical figures, including members of the Directory, the influential Madame Tallien, and even the epicurean figures Cambacérès and Brillat-Savarin, alongside a brief appearance by Talleyrand.

The Lyons Mail case is presented as a particularly complicated and interesting criminal problem, noted for its enduring mystery. The book draws attention to the famous theatrical interpretation of the case by the Irving father and son, highlighting its cultural resonance. Oman's work aims to untangle the historical threads and the involvement of various prominent figures of the era. The narrative suggests a deep dive into the historical context and the personalities involved in this complex affair.