没想到世界末日突然降临，山洞被毁，一家人被迫离开家园，展开一场全新的旅程。离开了居住了“一辈子”的山洞，展现在他们眼前的是一个崭新绚丽却又充满危险的新世界，到处都是食人的花草和叫不出名字的奇异鸟兽，一家人遇到了全所未有的危机。在旅途中，他们还遇到了游牧部落族人GUY，他有着超凡的创造力和革新思想，帮助咕噜一家躲过了重重困难，途中他还发明了很多“高科技”产品，并让他们知道了原来生活需要“用脑子”，走路需要“鞋子”等等。一行人在影片中展开了一场闹腾而又惊险的旅程。
疯狂原始人经典英语台词：
Guy: This is called a brain. I think that's where ideas go.
Thunk: Dad, I don't have a brain.
"Eep: My name's Eep and this is my family, the Croods. We never had the chance to explore the outside world because of my dad's one rule:
Eep: Never leave the cave.
Grug: New is always bad. Never not be afraid!
Eep: We never had a chance to explore the outside world, but what we didn't know was that our world was about to change."
"[Gran tries to eat Belt, the sloth, but Belt pulls a knife on Gran.]
Guy: Don't do that. He's not food. He's a pet, my pet.
Gran: What's a pet?
Guy: An animal you don't eat
Gran: We call those children.
Eep: [Smitten with Guy] Isn't this fun? We're taking our first trip together."
"Grug: Just think, our whole family packed together on a long, slow trip across country. We'll tell stories. We'll laugh. We'll become closer as a family.
[Sandy, the baby, bites Grug's face.]
Grug: Ah, get her off!
Ugga: If you're not ready to challenge her then don't look her in the eye!
Gran: Could you keep your big giant arms on your side of the trail?!
Grug: You want me to turn this family around? Do you? Because I will turn this family around so fast!
Thunk: Dad, I gotta go!
Grug: Come on, you can hold it.
Gran: I'm not dying on an empty stomach.
Ugga: Ugh, we're all pretty tired.
Grug: We'll eat when we get there.
Gran: It's taking too long! I'm grabbing a snack."
"Guy: We've gotta move faster. I call them shoes.
Eep: [screams] I love them! Where are my feet?"
"Eep: Oh, I've been in that cave forever!
Grug: Three days is not forever.
Eep: It is with this family.
Ugga: Mom, we're ready to leave. Mom?
Gran: Still alive!
Grug: It's still early."
"Grug: Ideas are for weaklings."
"Guy: Who are you.
Eep: OH! Eep.
Guy: Let me clarify Eep. The world is ending.
Eep: What
Guy: I am calling 'The End'"
"Guy: I am guy.
Eep: Guy.
Guy: And this is Belt.
Guy: Cook, conversationalist, navigator.
Guy: Also keeps my pants up.
Eep: What are pants up."
"Guy: Belt, emergency idea generator activate!"
"Grug: Never not be afraid."
"Thunk: You need a name, I think I'll call you Douglas. Roll over Douglas."
