Out of fuel, the crew of the Lexx has no other choice than to enter stasis while the Lexx drifts through space - looking for something to eat. 4000 years later, Stan and Xev find themselves awakened by the mysterious and cruel Prince, the first inhabitant of the two planets the Lexx has settled into orbit around to make it up to the ship.

Stanley is rescued from beheading in the nick of time, when Prince learns that Stan literally holds the "key" to his victory over Water. Meanwhile, Kai crashes down on Water, encountering May - the sole survivor of the slaughter of her city by forces from Fire.

While Kai goes down to Water with a swarm of Moths to find food for the Lexx, Stanley struggles with Prince's proposition - blow up Water, or May dies again.

Gametown is attacked by Duke's forces in the stolen moths, though Kai manages to take back one and return to the Lexx with Bunny. Trying once more to go down to Water for food, Stanley decides they should go to Boomtown - the "all sex all the time" city... Meanwhile, Duke moves against Prince on Fire.

With their moth damaged in the battle with Duke's forces, Stanley, Kai and Xev are stranded together with the living Kai and Bunny on the deserts of Fire. They find an abandoned balloon, but it does not have enough fuel to carry them all to the nearest town until Kai volunteers to go the rest of the journey on foot. But then they come across Duke and Fifi...

Xev and Stan find their way into the towering city they landed on, but discover the inhabitants aren't exactly the friendliest or sanest around...

Kai, still disabled, is taken away to bureaucrat hell for an adjudication. Meanwhile, Stanley and Xev follow Prince underground, hoping that he will lead them though the maze of tunnels to where Kai is.

Back on the Lexx, Stanley deices blowing up Fire and having the ship eat the debris would be the easiest way to it up an running again, and orders it to fire the next time it is pointed towards the planet. Xev demands Stanley let her take a turn as captain, and starts looking for ways to transfer the key from him to her.

Stanley starts to consider settling on Water, doubting that the dark universe holds anything better. When they go down to the planet looking for food, he finds the town Garden to be a promising candidate for permanent residence.

Prince's forces attack Garden, and kidnap Xev. Stan and Kai hijack one of their crafts and take up pursuit. But the enemy starts to manoeuvre in place above them, firing arrows to puncture their balloon.

Stan and Kai crash down on Water. Kai starts to sink towards the centre of the planet, while Stan drowns. The security guard is awakened on a beach by Prince, who tells him he now has to account for his life - prove that he deserves to spend the rest of eternity on Water, rather than Fire.

Xev and Kai go to Fire to confront Prince about Stanley's life essence. When he refuses to give it up, Kai jumps down into a well to the planet's core hoping to retrieve it. He winds up on the beach, with Prince taunting him that he's now trapped there for eternity, unable to help either Stanley or Xev.