Maki lives with her husband and her younger brother-in-law, Tsuyoshi. One day, she succumbs to Tsuyoshi's seduction and falls under his control. Trying to escape her husband's gaze, she is secretly fitted with a vibrator under the dinner table and teased relentlessly, while her heart is stolen by thrilling sex right beside her sleeping husband. Tsuyoshi's friends soon get involved, one after another joining in, escalating into wild group sex, and Maki is completely swept away by the tide.