Doctor C. has built a giant amp for Mike and Phil unplugs it because the noise is keeping him awake. The experiance reminds him of another story from long ago about Cro.
Cro wants to play in the marching band and Phil tells him that he should play the violin. Cro asks several of the mamoths and finally finds out just what a violin is and along the way learns about all the other musical instruments. He finally builds the violin but does not play it well. Big Red and his lacky, Murray, convince Cro that they want to help him. It's all a devious scheme for them to get the young Steamer for a dinner later.
They build a giant violin and take part in the tryouts for the band and pass with flying colors. Later that evening, Big Red hides a pack of dire wolves in the giant violin and the next day, they grab Steamer as he looks for his whistle behind the violin. The band starts to play and Cro notices that the violin doesn't sound the same, it sounds muffled. He discovers the wolves and tells Phil. Pandamonioum ensues as the mammoths and neanderthals beats up the wolves and the violin is destroyed. Phil has an idea and the wolves are tied to the platform and they howl in tune to the band with Cro directing.
Back to the present, Mike is trying to get the amp plug from Phil and fails. He tells Phil that he is too old to appreciate rock. Phil plugs in the amp and proves otherwise.