Thunk goes missing after the Thunder Sisters dismiss his help during a battle. The Thunder Sisters, and Grug, Phil, and Guy's newly formed "Thunder Sifters" search on and off the farm for Thunk.

The Croods, Bettermans, and Guy compete in the Throw-Go-Bowl - an annual Throw-go-nut championship game against the punch monkeys. Grug's desire to win above all else threatens to push away his teammates.

Phil enlists the Croods to help him retrieve a rare fruit before some wild animals can. But when Grug doesn't trust Phil's methods of getting it back to the farm, the Croods and Bettermans compete with each other more than with they did with the animals.

When the parents find their precious outhouse destroyed, they perform a "trouble trial" to find the culprit. To prove their innocence, each kid provides their own explanation for the outhouse's destruction.

After a big argument between the Croods and Bettermans, the parents decide to separate the two families. Not wanting to split up, the kids try to convince the parents to make up before the Croods move off the farm entirely.

Hwam returns with news of a utopian cave community, accidentally reigniting the argument between the Croods and Bettermans. As the Croods journey to Caveana and the Bettermans adjust to life without them, the parents deny how much they miss each other.