Accidental Swingers

While vacationing, Jim and Debbie meet a couple who assume they are there for the monthly mixer of the local swingers' club. After a good laugh, Jim is astounded when his demure wife agrees to attend the mixer. It can't hurt to just talk, can it? What they find are pleasant, ordinary people. They decide to attend one of their retreats, but with ground rules. Can they follow them?