When wealthy financier Daniel Horbury is found dead in his countryside home, it appears to be a suicide. But inspector Hanaud of the Paris police suspects foul play. He teams up with socialite Julius Ricardo to investigate, and they discover ties to a mysterious chart, a deported criminal named Bryan Devisher, and a troubling letter Horbury sent to shipping magnate Septimus Crottle. As Hanaud and Ricardo follow the clues, they uncover secrets, jealousies, and the darker sides of the characters involved. Their search for the truth leads from the elite of London society to the back alleys of Cairo.