In the tradition of the old "Ace Doubles" two-in-one books (flip one over to read the second title)--here is the fourth Wildside Mystery Double:
DEVIL'S PLAGUE: A Mystery Novel, by Michael R. Collings.

The scene lay tranquil and peaceful--except for the young woman's body, battered and broken at the foot of Porcupine Falls. Who was responsible? Was it the local boy, enamored and fearful of rejection; the stranger with the hidden past; or a serial killer? It's up to Lynn Hansen, recently arrived from L.A., and her new friend, Victoria Sears, to explore the intimacies of death, and solve the mystery of the Devil's Plague!

DRIVING HELL'S HIGHWAY: A Crime Novel, by Gary Lovisi.

He had no past and no future, only the long open road ahead of him. What would he find there, other than danger and violence? Sometimes a shred of memory, dark and fearful, gave him a hint of what he'd once been. Now he was just a loner. Darkness shrouded his heart and mind. With a trunkful of guns and a tankful of gas, he was Driving Hell's Highway! Hard-boiled crime in the 1950s paperback tradition.