The Wife-Swap Report — Lawrence Block

This was John Warren Wells' first book for Dell, consisting of a single case history explored in detail. Here's the publisher's blurb:

"Meet the Gordons...

"They're the very picture of a handsome, happy, healthy couple. Paul has a good job in the city, Sheila takes fine care of their pleasant suburban home, and they have three attractive young children.

"Like most married couples, Paul and Sheila like a night out. But their idea of a party is to join with other like-minded couples for an evening of sexual adventure, just as their idea of an enjoyable weekend is to visit an isolated lodge for a continual orgy of sex in every variety.

"This is their story. You may not want to believe it. But you'd better, because it's happenings all over the country today..."