Burgundy's Inspector Pel (Pel and the Pirates, etc.), somewhat mellowed by marriage, faces a complex puzzle triggered by a double murder. Rich, cultured Serrano Navarro, seemingly retired from criminal pursuits, and his bodyguard have been killed by Mark Donck, another educated crook. Meanwhile, Navarro's secretary-mistress, Jacqueline Herue, has disappeared; so has his brother-in-law, Henri Martin, a writer and one-time history professor. They all appeared to share an unlikely interest in the short-lived era of Emperor Maximilian in Mexico. When Donck is arrested after a bank robbery in Mexico City, Pel and his aristocratic aide, De Troquereau, are dispatched to bring him back--only to have their quarry escape jail soon after their arrival. Donck continues to elude capture, but Pel finds Henri Martin, another murder victim, and--after much research in the hill towns where Maximilian ended his days--begins to see the motive behind it all. Yet another killing awaits when he returns to France, where eventually an elaborate trap gets his man and ends an exotic change of pace from the usual police-procedural activities--present, but much downplayed in this outing. Original plotting, some intriguing history, and a bit of foreign terrain make this one outstanding in the Inspector Pel series.