The "wild at heart" in this film are a young couple in love, Lula and Sailor. She's a trashy, southern belle type who is really quite sweet. Sailor models himself after Elvis and is on parole from prison where he served time for killing a man in self defense. Lula has a neurotic oversexed mother who tries to seduce Sailor. When he rejects her, mom hires a hit man to kill him. Sailor decides to flee to California and Lula goes with him, but they run into trouble along the way.

There is a minimal amount of animal action in Wild at Heart. Dogs playing, a turkey and various bugs are seen briefly. In one scene a man has his hand blown off and afterward a dog is seen running out of the building with the hand in his mouth. The dog, of course had a fake rubber hand in his mouth.