Beginning in violence and terror the reader sees through the eyes of a man working with the challenge of finding himself in the middle of a great evil. He struggles to avoid becoming evil himself.
He has tried to save the wife of a mob boss only to experience her being brutally murdered and barely escaping a brutal attempt on his own life. In the end he is saved by a band of Mexican Indios.
After recovering he decides to go back and extract vergence. In the process he has to examine his own soul, his own nature to learn what he is capable of.
A satisfying conclusion. ( )

This is one of the best (maybe THE best) story about a man losing himself to find himself I've read. Published when MacDonald was just beginning his masterful reign of 30 years, it still works today. ( )

I enjoy all of MacDonald's pulp mysteries, mostly for light bedtime reading, but this one stands out. A surprisingly introspective and insightful ending knocks this one out of the formula and into the realm of literature.