《疯狂原始人》是讲述一个原始人家庭冒险旅行的3d喜剧动画片。原始人咕噜一家六口在老爸grug的庇护下生活。每天抢夺鸵鸟蛋为食，躲避野兽的追击，每晚听老爸叙述同一个故事，在山洞里过着一成不变的生活。大女儿eep是一个和老爸性格截然相反的充满好奇心的女孩，她不满足一辈子留在这个小山洞里，一心想要追逐山洞外面的新奇世界。
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."