Engineering college professor Don Ellis and his student, Lyda Darrow, are in love, but she refuses his proposal on the grounds that marriage destroys true love. Nonetheless, Lyda takes Don home to meet her wealthy mother, who happily accepts Don into the family. Lyda and Don spend a night out on the town and, at a speakeasy, overhear Eve Haron and Honey Rogers professing their love for each other. When Eve faints, Lyda helps her outside and hails a cab for her. On the way home, Lyda realizes that Honey stole her purse and tells Don about it to deglamorize Honey's declaration that he is going "straight" so he can marry Eve. Not wanting to marry Don and move to Colorado, where he dreams of building a dam, but afraid to lose him, Lyda lies and tells him she is pregnant. When he discovers her lie, he leaves her. Despondent, Lyda gets a letter from Eve and visits her at a home for wayward women. At Eve's request, Lyda visits Honey in prison and later helps Honey and Eve escape. Unfortunately, Honey accidentally kills a guard in the process. Alarmed by Lyda's disappearance, Don arrives to help her mother search for her. Eventually, the police track Eve and Honey to an apartment. Unable to bear another separation, they commit suicide, leaving Lyda to take the rap for harboring fugitives. She is arrested, but the district attorney agrees to drop the charges if she signs an agreement saying she was forced into her actions. Finally convinced of Eve and Honey's total devotion, Lyda refuses to sign, and Don promises to stand by her no matter the consequences.