You're back staying with your stepparents during the spring break and you've gone out clubbing, having probably had a few too many. When you barge into step-mom's bedroom in the middle of the night, she tries to send you back to your own room, warning that you're lucky your step-father's passed out on the couch downstairs. But you persist and when she refuses again, something drives you to lean in for a kiss. She tells you off but decides it's not worth fighting with you right now. You can stay in step-mom's bed as long as you leave early in the morning. You can't stop apologising as she comforts you, telling you to get some shut eye but you eventually drift off. Only to wake up to a sight you'd never thought you'd see.
I can't stop thinking about that kiss. How my step-son's lips felt on mine. How wrong it was, but how... hot. With my good-for-nothing husband leaving my bed empty yet again, I've not felt so desirable in years. I know I shouldn't, but he won't even know. I start touching myself, fantasizing about my step-son's touch.
When she notices you're awake, step-mom is horrified but you tell her it's ok. You're still horny too and now that you've sobered up, you just want her even more. She tells you no, but you grab her and start kissing her again and suddenly all inhibitions are gone. You fuck your step-mother frantically and passionately right there in your parents' bed until you both cum.
The next morning, in the sober light of day, step-mom warns you to never speak of what happened. Last night, stepmommy made a huge mistake. Only, it's not just the guilt playing on her mind that's got her unable to stop thinking about that night...