Lt. Thomas Mullin, retired against his will but almost glad to be free of the searing dusty desert around Fort Davis. A hard life in a hard place for a black man in a white man's cavalry. The US Cavalry was glad to be rid of him, too .. until a US Senator's son disappears in the desert and someone realizes that Mullin was the best tracker around.

Mullin quickly discovers that quite a few travelers and cowboys have recently disappeared without a trace in the exact same area. Here was a problem that no self-respecting reader of the Strand Magazine could ignore. No devotee as religious as Mullin could pass by a mystery as strange as this. Why, it would curl the hair of Sherlock Holmes himself ..

Consider the evidence: An empty, desolate, and inhospitable area where no patrols have found any trace of the missing men. A mystery without a scrap of evidence to examine. Unless you happen to have devoured the methods of the great sleuth of Baker Street, or happen to have a logical and brilliant mind able to piece together scraps of seemingly unrelated information and find a pattern . But what do you do when that pattern points to the impossible? And what do you do when the Senator hires drunken Pinkerton detectives to help you with the case? And, finally, what do you do when you've solved the puzzle and stand in the broiling sun facing a killer stranger and more deadly than any found in the pages of the Strand?