Part 1: After HAMMERER, Mary Alexis and George thistle all come together to scheme, Po and company must fight to stop them. Then, they fail miserably. Atlantis is lost and Po is missing. Part 2: After finding Po, James designs a time machine so they have the chance to stop the nightmare from even beginning. Part 3:After nearly succeeding, Po sacrifices the unthinkable to send the others home. The origin of Atlantis is revealed.