Deep in the heart of upstate Michigan lies a secret paradise: Warm Lake, so named for its unseasonable temperatures, even when there's a blizzard burying the whole state in a foot of snow. Keith and his girlfriend, Lucy, bask in the tropical climate with their friends, Dave and Torrie. With no tourists around, it's a perfect getaway.

But there's something strange about Warm Lake. And it's not just the weather.

With no warning, Keith and Dave find themselves missing an important aspect of their masculinity—while their girlfriends have gained something extra! Except, the girls don't realize anything's changed. And they're looking to have a lot of frisky fun!