A cave family called the Croods survives due to the overprotective nature of their stubborn, stern patriarch, father, Grug. The only one who questions the family’s sheltered life is his teenaged daughter Eep who frequently disobeys her father’s orders out of curiosity, which he finds dangerous. Grug and Eep, along with her mother and his wife Ugga, her grandmother Gran, and her younger brother and sister Thunk and Sandy face time sheltered in their cave home.
Eep sneaks out when she sees what she discovers to be a torch of fire and she encounters an inventive modern human boy named Guy and his pet sloth Belt. He warns her of an impending apocalypse and offers to take her with him, but concerned for her family, Eep stays, getting a shell horn from him to blow in case she needs his help. Reuniting with her frantic father, she tries to tell her family what Guy told her, but fearing things that are “different” and “new” Grug destroys her horn.
A massive earthquake then destroys their home, and to avoid the earlier carnivore, they descend down into a tropical forest that lay hidden behind their cave all the time. Encountering a “Macawnivore” a brightly colored feline that Gran dubs “Chunky the Death Cat,” the family flees him until he is deterred by swarms of piranhakeets that devoured a ground whale. Using another horn, Eep calls to Guy who rescues them from the birds with his fire. After a great deal of confusion regarding their first contact with fire, Grug imprisons Guy in a log until he can guide them somewhere safe.