"Geronimo Stilton's ancient ancestor Geronimo Stiltonoot is back in another prehistoric adventure! It's the night of the big Cavemouse Idol competition, but Geronimo Stiltonoot isn't there. He has a cold, and goes to bed early. So when it's discovered that the contest's valuable grand prize has been stolen, Geronimo is the main suspect! He must prove his innocence ... or he'll end up in enormouse trouble!"--Publisher's web site.