Showing Deadly Welcome by John D. MacDonald

Alex Doyle is a tough man on a tough assignment in Ramona Beach, Florida - the kind of place that doesn't trust strangers and is policed by a sheriff who echoes the locals' sentiments with a billy club. But Alex isn't an outsider, exactly. He grew up in Ramona Beach - until they railroaded him out of town. 'Can't trust trash,' they said.

Alex has never been back, until his employer sends him home to locate a government scientist and get him out alive. Unfortunately for Alex, Ramona Beach has a long memory. Unfortunately for Ramona Beach, so does Alex.