Amelia, the new girlfriend, is curious about her boyfriend Robert's close bond with his stepsister Grace. One day, she walks in on Grace, naked and spread-legged, as Robert eagerly licks her pussy. Amelia, initially shocked, watches as Grace moans, her fingers tangled in Robert's hair. Robert looks up, unapologetic, and invites Amelia to join. Grace, her eyes heavy with lust, beckons Amelia closer, whispering, "He's so good with his tongue."