They get to an exit from the Underworld and Jack goes to use the key they were down there for to open it, but he drops it. One of the Machina guys below them catches it, then Ikira leaps down after him and swipes the key again, tossing it back up to Jack. Jack manages to get the door open this time, letting sunlight into the tunnel as well. Jack and Ikira take off, but not before hearing the Machina screaming in pain because of the light.
Jack asks why the Machina can't handle the light, to which Ikira replies, 'the legends say they are cursed, atoning for the sins of their ancestors'. Xyber notes that he's never investigated and does so, finding that it's really a viral organism in the Machina's bodies reacting with the sunlight and causing them lethal pain. Ikira looks rather unnerved by this as they leave the area, but Jack mistakenly thinks he's upset over him dropping the key.
They get back to the New Valley, and Willy is checking over the jumper. It's damaged pretty badly and of course Mick has to complain about it. "You got the jumper all shot to pieces just for a lousy key?" Xyber explains that it's a very special key, one that can let them into any Machina tunnel entrance without setting off the alarms, and it could be quite useful. Mick wonders why the heck they'd want to go down there and says the Machina are just thieves and such. Ikira tells him, "Do not judge what you don't know, those who seem to be evil may only be misguided." Mick scoffs at this and continues insulting the Machina, and Ikira turns and walks away . . .
[commercial break]
It's night now, and Ikira is still up on that hill, looking at the two moons. Jack and Anakonda are down by the fire, and the boy wants to go to Ikira but Ana tells him no, Ikira needs some time alone. Jack complains that he wants to help because Ikira's his friend, but Ana still won't let him go. The snake girl says that when one of her people is in pain, they want to be alone, but the rest of the tribe will sing a song for the one who's in pain to help them get through it. So saying, Ana starts to sing for Ikira in her own language . . . this naturally wakes Mick up and he's complaining up a storm as usual. Jack tells him to leave Ana alone because she's singing for Ikira, but this only gets Mick even more angry. Willy manages to calm Mick down, and Ana keeps singing, while Ikira still stands alone on the hill . . .
A bit later on, when everyone else is asleep, Ikira comes down off the hill and takes the key from Jack, whilst avoiding the Xyber's watchful gaze. Ikira gets on his speeder and takes off, leaving the rest of the group to find the key's been stolen and that the old warrior is missing . . .
[commercial break 2]
The group is out looking for Ikira now, with Ana doing her usual job as tracker. She manages to trace Ikira to what looks to be a big rock in the middle of the desert, but some further investigation by Willy reveals it as a Machina tunnel entrance. Mick says he's always been suspicious of Ikira and that now the old guy's gone over to the Machina's side. Jack refuses to believe this, and Xyber says something about giving a motivational speech. Jack however has a different idea and jumps on his vehicle, blasting a hole through the fake rock. He doesn't care what the rest of them are going to do, but he's going after Ikira. Ana hops on with him, to keep him from doing anything foolish, and Jack flies off into the tunnel. Mick complains that he's not going down there, but Willy says he'll be on his own. Mick tells his friend he's too trusting, but then goes with him anyway.
Meanwhile, Ikira is farther ahead in the tunnel, and jumps a Machina to steal his hoverbike and armor. Now in disguise, Ikira takes off down the tunnel, to where the rest of the Machina are gathering. This disguise isn't enough to fool Machestro however, as he observes the warrior flying off. Dakartar asks if they should postpone the gathering but Machestro tells him no, telling the lackey that Ikira could prove quite useful.
The gathering gets underway, with the droves of Machina chanting Machestro's name . . . the dark lord goes into something of a motivational speech of his own but doesn't get to finish as Ikira reveals himself and calls Machestro a liar. Machestro orders his soldiers to silence Ikira immediately . . . the warrior says about bringing a message of hope but gets his speech interrupted as he's shot down and captured.
Ikira is brought before Machestro, who wonders what that 'message of hope' could have been. "The Machina are not cursed, it is a virus!" Ikira says, and Machestro orders the guards to leave. The dark lord tells Ikira that he's right, and that sunlight is the cure to the virus, if you can survive the pain. Ikira demands to know why Machestro hasn't told the Machina about this, to which he replies, "I am about to conquer a world. What need have I of a cure?"
Ikira asks him 'What madness is this?', and Machestro says it isn't madness but reality. Then the dark lord tells Ikira about the Eye of Darkness, a device that will spread darkness over the entire planet, allowing his legions to rule the surface. That's the only cure that Machestro wants. The final piece to this doomsday device is Xyber 9, which Jack is bringing directly to him since the boy is coming to rescue Ikira . . . Ikira only has one thing to say about this, "By the Oath!"
[commercial break 3]
Jack and company are fairly deep in the tunnels now, with Ana tracking Ikira's scent. "There was a struggle here, then he went this way," she says, and Mick asks if they can trust her nose. She says it'd be easier to follow Mick, since he stinks! Mick does an armpit check and says he's had his bath for the month, then the group moves on.
The gang winds up in a large room, probably near the center of the Underworld, and Ikira is hanging off a huge device (I'm assuming this is the Eye of Darkness) in the middle of the room. Xyber takes a good look at it and says Machestro would never be foolish enough to activate it, as it would polarize every particle in the atmosphere and nothing can live without light. Ana has her own interpretation of this, "This is the center of darkness, and this is the heart of death." Mick is creeped out by this and says let's free Ikira and get out of here.
Before our heroes can do that, they find they've been surrounded by Machina. Machestro is among them, of course, demanding the Xyber. There's a bit of a conversation, but Machestro eventually reveals that Ikira is a Machina. Jack doesn't believe him, and orders Willy to get Ikira down. Ikira falls to the floor, Ana goes over to check on him and Jack's about to as well, when Machestro asks for the Xyber again. He'll let them all go free if they'll give him the Xyber, but Jack isn't buying it. "I'll smash it to bits before I'd give it to you!" Machestro knows Jack would never do that to the Xyber, but makes the mistake of calling Jack 'boy'. We all know what happens when someone calls him that by now, don't we?
Jack growls "Don't call me boy!" and pitches the Xyber into the air. He hops back on his jumper and flies up to retrieve the Xyber, and the battle is on! The whole group is fighting the Machina army, blasting Tunnel Rats left and right. But there's a very serious chance they'll be overwhelmed by the sheer numbers of them so Mick says, "This is getting repetitive, let's go home!"
The whole group takes off for the surface, with the Machina in hot pursuit. Willy fires a missile from the halfback and wastes most of the Tunnel Rats behind them, but Machestro's transport breaks through the cloud of smoke and debris, unfazed by the attack. The tunneling machine returns missile fire, but Ikira is ready for it, slicing the projectile in half with his blades. The warrior reminds Jack about his speeder, and Jack has the Xyber call it. Ikira reclaims his vehicle and they keep going.
Ikira tosses the key at the tunnel exit and it opens, letting everyone out onto the surface. A lucky shot blasts Mick from his perch on the halfback, though. He tells Willy to keep going, to make sure the rest of them get back to the forcefield at the New Valley. The thief is rather amazed at his own actions, but doesn't have time to think about it cause the Machina are still barreling up the tunnel! Mick opens fire with his blaster, but is soon rescued by Ikira.
The Machina are still tailing them, making our heroes see just how fast those vehicles of theirs can go. Machestro isn't about to let them escape, but he doesn't really have a choice as Jack and company manage to make it through the forcefield before they can be caught. The Tunnel Rats slam into the forcefield, exploding on contact. Machestro's transport can't stop in time either, and most of it is consumed by the energy barrier, but the dark lord is lucky and doesn't get fried himself. It's an awfully close call, though, as the barrier stopped right in front of him.
Machestro manages to get out of the wrecked transport somehow, and swears once he finds them outside of their sanctuary, he'll crush them with the full power of the night . . .
I suppose it's either a few minutes or possibly an hour later back at our heroes' camp, and Ikira tells them his story. Machestro was telling the truth, Ikira is Machina. He was betrayed and left to die in the sunlight, but was rescued in time to survive the pain. Mick asks if the Machina could be normal like them, to which Ikira replies, "I would never describe you as normal." Mick's amazed the old guy could actually make a joke . . .
Probably a little while afterwards, Ikira and Jack are on the hill from earlier. Jack was afraid Ikira wasn't coming back, and the old warrior admits that he was wrong not to tell the boy. Ikira promises him that from now on, Jack will always know where he is. Jack says he'd like that . . .