Mei Lee and Jason from Sealab, are exploring the recently-discovered deepest underwater trench, when their sea-bubble is attacked by a giant squid. Max is sent to rescue them but suffers the same fate. Ace and Jake are in NASA to use an experimental Venus Probe, the only probe that can withstand the pressure at that depth. There Ace faces his old Air Academy comrade Sean O'Connor, who still holds a grudge against him over a girl. Max comes through to find himself in the undersea city of Atlantis, ruled by Princess Diana. She tells him of the city's century survival as well as the reluctance for communicating with the outside world. The princess refuses to ever let Max, Mei Lee and Jason. Meanwhile Diana's cousin Naro plots to take over Atlantis.