Francis Elton, a field service engineer, arrives in Chihuahua, Mexico, in response to a desperate phone call from his former wife, Alicia, just as she was being detained at the city jail. Alicia, an American artist, is accused of shooting and killing the restoration project's director, Professor Salazar, when the two of them were alone together and locked inside Pancho Villa's Museum. Seemingly, no one, other than Alicia, has a motive, and everyone, but Alicia, has a rock-solid alibi for the time of the murder. Add to that a recently fired Colt 45 revolver, wiped clean of fingerprints, found returned to its holster in an exhibit room, not far from the Professor's lifeless body. Knowing that only Francis would believe in her innocence, Alicia presses him into a search for the real killer. But Francis has only the analytical method he uses to troubleshoot broken industrial machinery to apply to the task. And when it comes to murder south of the border, that approach may not translate so well.