The priceless Zubble-Wump egg has been in Megan Mullally's family for as long as anyone can remember, so when the Grinch steals it, she sets off with Horton to get it back. The egg is on the verge of hatching, and no one may get to hear the Zubble-Wump's exquisite song unless Megan and the Grinch stop being so greedy.