The train's motion lulls them into a false sense of privacy, but the couple can't resist their primal urges. She hikes up her skirt, revealing her lack of underwear, and he takes the hint, pulling out his throbbing cock. She guides him into her, and they start fucking hard, the train's motion amplifying their thrusts. The thrill of public sex is intoxicating, and they can't get enough, switching positions, her riding him reverse cowgirl, his cock slapping against her ass. As the train pulls into a station, they quickly compose themselves, leaving behind a steamy window and the lingering scent of sex.