Determined to start the new year off right, dress designer Geraldine "Jerry" Trent sends her unfaithful boyfriend, Jim Woodward packing.  A short time later, her friend Buster Collins introduces her to author Tony Blake.  Jerry loves Tony's book, Obey That Impulse, and finds him attractive as well.

Practicing what he preaches, Tony immediately proposes marriage.  Jerry just laughs, but together they have a lot of fun acting out Tony's theory, and she soon realizes that she loves and wants to marry him.  First, though, she feels she must tell him about her affair with Jim despite dire warnings from her Aunt Kate.  Although he's upset by the news, Tony still wants to marry her.

The next day, Jerry's sister Joan arrives home from school in France where, unknown to Jerry, she has fallen in love with Jim.  When Jerry finds out, she warns Jim to stay away from her sister, but he doesn't take the situation seriously and invites everyone to his parent's house party.  Initially, Jerry refuses to go, but when she finds out that business will prevent Tony from attending, she decides to go after all and keep an eye on Joan.

Desperate to break Joan's engagement, Jerry first pretends to be a little crazy.  When this doesn't work, she pretends she is still in love with Jim.  While the two of them are alone together, she signals to Joan for help by singing a special song. Joan comes to her aid only to see Jerry and Jim embracing.  Unfortunately, so does Tony, who has arrived at the last minute.

Heartbroken, Jerry returns home, where Aunt Kate convinces her to pursue Tony who is sailing for Europe.  Jerry sneaks on the boat in the seat of a car and finds Tony who asks the captain to marry them immediately.