Sia Lust and her stepbrother, Nathan Bronson, have gotten together in the past. Their fuck fest was supposed to be a secret, but Sia couldn't stop herself from sharing with her best friend, Lily Larimar. When Nathan drops into Sia's room to deliver her cell phone that she left lying around, Sia gives him a hug. Lily picks up on how awkward they are and asks if it's because they boned down. Nathan and Sia are unhappy with Lily for talking about it, but Lily stays the course. She claims that it's national brothers day and they should therefore get together again so Sia can prove how much she appreciates Nathan being her stepbrother.

When Lily's initial idea doesn't work, she isn't done. She turns to Nathan and claims that Sia says he has a really nice dick and she wants to see it. Nathan eventually gives in to Lily's pleading. Once Lily has admired the D, she begs Sia to stroke it. While Sia is doing as Lily wants, she finds that she's unbearably turned on. She needs the cock so much that she begs Nathan to give it to her, with Lily's blessing of course. On her knees, Sia takes a proper pussy pounding courtesy of Nathan as Lily watches and masturbates to the sight. They get Nathan on his back so that Sia can climb aboard and enjoy herself in cowgirl. When Sia falls onto her back, Lily manages to convince Nathan to glut his stepsis with a big ol' creampie.

Dripping with her stepbrother's jizz, Sia dismisses Nathan, telling him that they're done with him. When Nathan is gone, Lily licks the cum from Sia's twat. While she's enjoying her treat, she arranges herself so that her pussy is overtop of Sia's mouth, creating a lesbian 69. The girls enjoy each other's most tender bits for a while, but it's not quite enough to make either of them cum. They get there by going pussy to pussy and tribbing together. As their scissoring brings first one and then the other to climax, they fall backwards and bask in the afterglow of a raunchy time together.