The Ravagers — Donald Hamilton

It was not a peaceful way to die, but there was nothing Matt Helm could do for his fellow agent. He had found him in a Canadian motel room, his once-handsome face eaten away, corroded by acid. Scratch one agent. The women wouldn't be lining up for him now. But it created further problems. The most likely culprit was a woman Helm had orders to protect - no matter what the cost.