The Dazzling Miss Davison(1917)

Young society rake Gerard Buckland spies a pretty girl walking down the street. As he tries to figure out a way to approach her, he sees a disreputable-looking man surreptitiously hand her a diamond necklace, which she hides on her person before fading into the crowd and disappearing from sight. Later that day he visits a friend's home, and is astounded to meet that same girl. During their conversation she claims that, as a lark, she picks her friends' pockets of valuables and gives them back later--but Gerard doesn't quite buy it. It turns out that she is, in fact, not what she says she is, but not in the way Gerard thinks.