In the throes of teenage hormones, a brother and sister find themselves alone, their curiosity piqued. She starts by touching herself, her moans barely contained, while he watches, his cock hardening. Caught in the act, they argue, but the tension's too thick. Soon, they're naked, her fingers tracing his length, him exploring her wetness. Just as they're about to cross the final line, a creaking floorboard stops them cold.