They meet on a subway train, where the guy tells her about a secret photo booth that takes pictures on old film. Their chance encounter turns into a romance and a date that changes both their lives. But he becomes obsessed with the mysterious key hanging around her neck, convinced it is connected to a hidden secret. After a passionate night together, he mysteriously disappears the next morning. Who is he really? Why did he vanish? And what does the key unlock? Perhaps he has a secret of his own that he never revealed.