Eep (Emma Stone) is a girl in a family of cavemen living and hunting in pre-historic times. Her family is one of the few to survive, mainly due to the strict rules of her overprotective father, Grug (Nicolas Cage). In their cave home, Grug tells a story to the family, which includes his wife Ugga (Catherine Keener), his daughter Sandy, his son Thunk (Clark Duke), and his mother-in-law Gran (Cloris Leachman). He uses the story of a character who mirrors Eep's curious nature to warn the family that exploration and 'new things' pose a threat to their survival, and says to never not be afraid. This irritates the bored and adventurous Eep, and after the family falls asleep, she leaves the cave, against her father's advice, when she sees a light moving outside.