On a packed train, a man spots a woman's skirt accidentally flipped up and secretly jerks off behind his bag. The woman beside him catches him, but instead of getting angry, she tells him to keep going, watches him masturbate, and gives him a handjob. Then he learns she is friends with the woman whose panties he was watching. The pair seize on his secret, tease his cock and suck him off on the train, then move somewhere deserted to punish him in a threesome.