Momo has grown distant from her work-obsessed husband and increasingly uncomfortable in their marriage. She becomes attracted to the younger brother-in-law living with them, and a forbidden romance begins. They promise to go no further than kissing, deepening their secret love through passionate exchanges of saliva. Desire soon overwhelms them, and despite her lingering feelings for her husband, they cross the line into repeated creampie sex. The story follows the pair as love and lust consume them.