With the economic downturn over the last several years, there are probably quite a few fathers who can relate to caveman Grug Crood in some small way. Just keep your head down, nose to the grindstone, keep doing things the way you’ve been doing them for the last 20 years, and you’ll somehow keep the family going. But then, disaster strikes, and there’s no choice but to venture outside your comfortable confines in order to survive. For the Croods, the disaster is a lot worse than a layoff or a defaulted mortgage; their home is destroyed as their entire world quite literally comes crashing down around them. The only thing Grug, wife Ugga, mother-in-law Gran, eldest sister Eep, middle son Thunk, and feral toddler Sandy can do is run into the great unknown of a jungle they never even knew existed.
While there, they meet Guy, an idea man with a slightly more rounded forehead who has survived alone by his wits, cunning, and a little help from his sloth pants-holder-upper/comic relief sidekick, Belt. Guy creates fire to keep predators away at night, he understands the concept of shoes, and can set elaborate traps to snare food. He also has a plan: to get to the high ground before this thing he’s calling “the end” catches up with all of them. But Grug doesn’t like change…and he doesn’t like the way his teenage daughter is so enamored with this new Guy, either.