The "Down the Tubes" saga continues with part 2 of 4! Making final preparations to take over The Universe, the power-hungry Apex begins to systematically eliminate all potential adversaries, starting with Portal's friends! Meanwhile, Dave and VAL concoct a plan to return to The Hub... but will it be too late? Also in this episode: Dr. Julia Hopkins continues her search for Dave's betrayer. Is something wrong with Grooter? And the birth of the most unexpected hero of all...