Detectives and their partners are considered to be a common motif in mid-century fiction, but actually you don't run into pairings as often as you'd expect, and when you do, one character usually dominates the narrative. End of the Line, by Bert and Dolores Hitchens, features two detectives in a story that's almost equally divided. Maybe that's what happens when spouses collaborate. The two detectives work for a railroad company and are tasked with investigating a cold case—the Lobo Tunnel crash of five years earlier, in which a train was derailed by a deliberately placed obstruction. The mystery is fine, but the fun part is reading how the two sleuths—one a mama's boy and the other a heavy drinker—try to work together. The Pocket Books paperback you see here has beautiful cover art by Jerry Allison that suggests the story is about a girl in trouble. That's true too, but it's the dicks that make this one swing. Pretty cool stuff, copyright 1959.