A giant pie is sent to Pretty Big City to stop an asteroid... but that discovery is made only after the Mechas and friends have eaten the whole thing. Now it's up to the Mechas to find a replacement substance to catch the asteroid. / The Singing Stone Heads are ready to perform at Big Old Boulder Museum, but when they open their mouths, the only sounds that come out are sneezes! The Mechas have to figure out what's causing the sneezing and how to stop it to save the concert.