Times are changing for Manny the moody mammoth, Sid the motor mouthed sloth and Diego the crafty saber-toothed tiger. Life heats up for our heroes when they meet some new and none-too-friendly neighbors – the mighty dinosaurs.

Jimmy is the kid everybody ignores and uses. One day, he gets into a freak accident. The only way for him to survive is a brain transplant. He gets the brain of Milt Appleday, a famous cartoon creator. And when he wakes up, he can see cartoons!

After making it to the top of the charts, members of the Silver Boulders, a popular tween rock band, find themselves undermined by internal squabbling as the bandmates seek different creative directions.