The Deep Blue Good-by by John D. MacDonald
It's easy to see why Travis McGee's legend endures. He's a white knight in tarnished armor, a decent man who lives by his own moral code and personal philosophy on the outside of society, on a houseboat called The Busted Flush.
No stereotypical P.I., he's a self described "salvage expert" who will find what was taken from the innocent...for half of what he retrieves.
Although a character of his time and place, Fort Lauderdale, Florida in the 1960s, he is more timeless than dated, in my opinion.
Highly recommended.