After years of marriage, a bored couple has fallen into a sexless routine. When they confide in close friends, the other couple suggests partner swapping as a change of pace. The wife initially hesitates with tension and disgust, but one step into the experience plunges everyone into overwhelming pleasure. Watching their spouses get fucked stirs jealousy and arousal, drawing both couples deeper until ordinary sex no longer satisfies them—though their dead bedroom is finally revived.