In the heat of the moment, the curious brother finds himself alone in the house with his sister-in-law's panties. He can't help but run his fingers along the fabric, feeling the dampness that hints at her arousal. His mind races with images of her wearing them, her pussy lips visible through the thin material. He tentatively brings them to his face, breathing in her musk, his cock stiffening in his pants. He unzips, letting his cock free, and strokes it with the panties, his fantasy of fucking her in them driving him to a quick, intense orgasm.