Continues from X-Men #16. Stryfe and Cable battle on the moon with Cyclops and Jean Grey looking on, powerless, in an energy field that only those with the Summers gene can penetrate. Stryfe asserts that he is superior to Cable, that Cable was a clone and a mistake.
Psylocke psionically detects that Apocalypse is dying. Archangel finds him near death, defeated by his own Dark Riders. Apocalypse expects Archangel to kill him, but Archangel refuses and leaves him to die.
Meanwhile, Havok, having entered Stryfe's energy field, awakens after being knocked out by it. He attacks Stryfe, who loses his concentration, allowing Cyclops and Jean Grey to escape his hold on them.
Cable gives Cyclops a device that activates a time vortex, Cyclops activates it while Stryfe and Cable battle. Both are sucked into the vortex, to what is believed by Cyclops to be their deaths.
The epilogue features Mr. Sinister's assistant Gordon unwittingly opening the canister that contains the Legacy Virus believing it to contain the Summers DNA. The epilogue to this arc is found in Uncanny X-Men #297.
Mistake: On page 17, Cyclops' speech bubble is connected to Jean's, making it look like Jean is saying the whole thing. Cyclops speaks in the first bubble; Jean gets the other two.
Outside Stryfe's purloined moon base, Cable looks at a tower, atop of which is Stryfe with Cyclops and Jean Grey. Surrounding the tower is a force field that prevents anyone else from entering. Stryfe speaks in riddles about the ability to change yesterday from tomorrow and Cable refutes the notion. Stryfe then hits a nerve when he calls Cable a failed experiment - a clone that wasn't necessary. Cable refutes this notion with his gun by blasting the tower. Stryfe descends from the tower and furthers his taunts by stating that Cable doesn't matter, as it is Stryfe who is the whole person while Cable is just a half-life. The men engage while Cyclops and Jean look on. Cyclops wonders if Stryfe is really crazy or if something has simply set him off.
Inside Stryfe's purloined moon base, Psylocke, Wolverine, and Storm witness the Dark Riders make their escape. Wolverine begins hacking at things indiscriminately while Psylocke does a scan for Apocalypse. She senses him and realizes that he is dying. She communicates this information (both the escape of the Dark Riders and the condition of Apocalypse) to the other teams around the base. Archangel takes it upon himself to find his former master.
Just outside the force field, Polaris and Cannonball shake themselves from the jolt they received after trying to breach the tower. They notice two things: 1) Havok seems to have made it through, though he's not entirely conscious, and 2) Cable is engaging Stryfe one-on-one, which means that there isn't much hope. True to this fear, Stryfe seems to be handily whipping Cable; all the while, he spouts off the worthlessness of Cable's life. Cable refuses to give in and makes a valiant showing for himself, but Stryfe merely hits him with a psionic blast that shreds all of Cable's synthetic skin away from his metal parts. Half his body seems to be made of metal. Stryfe notes this and asks how Cable can even pretend to be a man.
On Earth, Professor Xavier is still reeling from the realization that Cyclops, Jean, Cable, and Stryfe are all linked by blood. He feels responsible for these tragic events and laments that Cyclops and Jean may lose their lives on his account.
Archangel finds the body of Apocalypse. The villain welcomes the sight of Archangel as he knows that revenge will be swift and the death of Apocalypse will be fitting one who has survived so long. Archangel realizes this. He proclaims that Apocalypse may have changed some physical features, but he will never have changed who Archangel really is. Archangel then walks away and leaves Apocalypse in his blood. Apocalypse screams after him that he must be allowed a death befitting a specimen such as himself but his cries go unheeded. He is left to die slowly and painfully.
Back within the force field of the tower, Jean prays that Stryfe's attention gets too strained so that she and Cyclops can break free of Stryfe's telekinetic bonds. Almost immediately, Havok blasts Stryfe with an incredible blast. Stryfe had made the force field to allow in those with the blood of the Summers family to pass through - he had forgotten about Havok's ties. He turns his attention to destroying Havok when he is blasted again, this time by Cyclops. Jean offers their help to heal whatever is ailing Stryfe. For a moment, Stryfe considers this offer. Ultimately, however, he charges them with lying, again, and lets out a huge burst of energy - the likes of which is felt by the accumulating X-Men outside the force field. With all these energies swirling around, along with pieces of the falling tower, Jean constructs a barrier for Cyclops, Havok, and herself. Cable is too far away. This matters little, as Cable has other plans. He quickly wires something together and throws Cyclops an engage switch. Cyclops doesn't know what to do with this switch but he's assured that he'll know soon enough.
Cable tackles Stryfe and the two struggle mightily. Stryfe refuses to be bested by a clone of himself. Cable demands that Stryfe recognize that Cable is his own man, a man who has made the decision to kill Stryfe. Cable hits a self-destruct button. Cyclops then knows what his button is for. With all the time flux energies whipping around, Cable wants the self-destruct and the time flux events to happen simultaneously. Cable wants Cyclops to kill him. Cyclops struggles with this decision but finally chooses to follow Cable's orders once the self-destruct is engaged. With an oath, Cyclops pushes the button and watches as a vortex is opened and Cable and Stryfe are sucked through it. Cyclops realizes that he has once again let his son go.
The tower is gone and the X-Teams gather around Jean's protective shield. The ordeal is over. Cyclops, however, will be forever wracked by his decision, as he feels he'll never know his relation to either Cable or Stryfe.
In Mr. Sinister's lab in Nebraska, Gordon opens a canister. This canister was traded from the Mutant Liberation Front for the bodies of Cyclops and Jean Grey. This canister was supposed to contain the genetic make-up of the entire Summer's family. It appears, however, that the canister is empty. Mr. Sinister has been duped. Unbeknownst to mutant kind, the canister was no empty. It's opening released the Legacy Virus.