Mister Justice, 1973.

Crammed into half an Ace double and never reprinted, Mister Justice remains in a class by itself: hardboiled America, sci-fi style. Here the 2030s appear as a mutated 1930s, complete with an economic catastrophe that threatens evolution itself. The Shadow, the Green Hornet, the Untouchables - they never had what Mr. Justice has going for him. Sprung from humanity's threatened altruistic genes, this masked vigilante has the ability to travel into the past, where he can witness, but not prevent, murders.

He then returns to the present, where he arranges an "eye for an eye" treatment for the slayers, including full-scale gangland rub-outs. But he can't easily dispose of one Arthur Bingle, global crime archon who has the same powers as Mr. J. and then some. Bingle feels about the human race in general what Mr. Justice feels about criminals, and he plans to thin us out and "empty the world." With the help of his powers, his syndicates of henchmen and corrupt cops, and his dreadful lady friend Godiva - she of the constrictor thighs - Bingle gets the drop on humanity. But justice is just a matter of time. Piserchia relates this furious folktale with Chandler soul, Hammett snap, and not a trace of camp.

Jim Trombetta, "The Coolest Sci-Fi," from The Catalog of Cool (1982), edited by Gene Sculatti, p. 87.