Shameful Behavior? (1926)
One time “plain Jane” Daphne Carrol returns from Paris a "polished" flapper. She sets her cap for her sister's brother-in-law, Custis Lee even though he is indifferent to her. When Custis’s brother, Jack, managing editor of the local newspaper prints a story of Daphne's return her picture accidentally appears over a news item about the escape of Sally Long from an insane asylum. Daphne gains entrance to Custis' house and poses as Sally, claiming him to be her husband. Fearful for his life, he humors her until he can engage a nurse to watch her. Daphne enjoys the joke until she discovers that her nurse is actually Sally--and Sally's husband tries to rob the Custis home. In the merry mix-up Daphne faints in Custis' arms and is forced to declare that she is his wife; after the complications are resolved, they decide to make the arrangement legal.
