Ella Knox walks into the house and calls out for her mom. When there's no response, she's thrilled to have the house all to herself. But her hopes are shattered when she hears a voice from the living room. When Ella walks in there, she finds Penny Pax on the couch looking sexy as fuck in her blue dress. When Ella asks who she is, she introduces herself as an old friend of her mom's. Clueless that they were expecting company, Penny tells Ella that she's been friends with her mom for ages and came to visit to get away from the daily grind of her life. When Ella excuses herself to go study for her biology exam, Penny tells her that she actually works in the biology department and could probably help her study. Feeling grateful for her offer, she invites Penny up to her room. What Ella doesn't know is that her stepmom, Reagan Foxx, coached Penny on what to say. Penny starts seducing Ella and it's clear early on that the only biology Penny's concern with is Ella's body. When Reagan walks into the house, she hears something coming from upstairs. When she realizes that the girls are fucking, she storms into the room and asks them what they think they're doing. Penny is Reagan Reagan's lover and Ella is feeling really weird about having fooled around with her stepmom's girlfriend. When she tries to leave the room, Penny stops her and says that it's fine; they've had different lovers before and it's not that big of a deal. When Penny convinces Reagan that perhaps they could smooth things over with a biological examination of Ella's body, both girls eventually warm up to the idea. In the end, it looks like Ella's gonna get an A +.