Synopsis
In #102 a Sentinel kidnapped Scarlet Witch, and last issue we learned that the Sentinels were causing solar flares. Quicksilver has brought Larry Trask, precognitive son of the Sentinels' creator, to the Sentinels' technological ant-hill in the Australian outback, where the other Avengers are already fighting 2 guardian Sentinels. Last issue saw Vision fall, but Captain America, Hawkeye, Iron Man and Thor battle on.
As Trask leads Pietro through a secret side entrance, Vision reveals that he was only playing dead. Attacking the Sentinels unexpectedly, he disrupts their circuits by phasing through them. And the Avengers descend into the giant underground complex.
On the lowest level of the base, the robots' leader Sentinel #2 explains his plan to the captive Wanda. He is using her mutant energy to power the solar flare ray. For some (unexplained) reason he needed a female mutant, and as an Avenger Scarlet Witch was the easiest to find. The Sentinels were built to destroy mutants, but not to kill non-mutants. #2 explains that the maximum solar flare will be nicely judged to render all humans sterile. When the last human being is dead, the Sentinels will create a new human race, without mutants.
Quicksilver and Trask have reached a locked door at the end of the side tunnel. Trask is suddenly hit by a repeat of his vision of last issue, predicting that Sentinel #2 will kill the Avengers, a solar flare will destroy the Earth, and after that nothing.
Quicksilver uses the vibrations of repeated high-speed attacks to jar the locking mechanism and open the door. Then he has to face a Sentinel. He lets it chase him and tricks it into smashing against a wall. But Pietro himself is severely injured by hitting the wall, and having the Sentinel fall on him.
He tells Trask to leave him, find Wanda and stop the Sentinels. After Larry goes, Pietro sees something appear in front of him.
The other Avengers fight their way down inside the ant-hill, while Vision slips away. Eventually they are confronted by Sentinel #2 and 3 others. #2 shows a simulation of the Earth being shattered by a solar flare, but explains that he will ensure that the flare isn't that bad, and will only sterilise humanity. Then the robot blasts the 4 Avengers.
But before it can kill them, Vision reappears with the freed Scarlet Witch. Wanda blocks #2's attack with a hex sphere, while Vision tackles the other 3.
Larry Trask has witnessed all this, and realises that he has seen 2 parts of his vision come 'true'. But he doesn't know what the succeeding blackness meant.
He finds a mutant detection device switched off. Starting it up projects a glow round himself and Scarlet Witch. But also round Sentinel #2.
When the Sentinels were sent to the sun, #2 was mutated. This gave him the ability to transport other Sentinels through space-warps, as seen in #102. It also allowed him to break the ban on harming humans, and attack the Avengers. (Presumably it also allowed him to consider sterilising humans as an acceptable tactic.)
#2 is preparing to initiate the final solar flare, when the other Sentinels turn on him because he is a mutant, and destroy him.
However his destruction also switches off all the other Sentinels. And one of then falls on Larry Trask, crushing him to death. Which explains the final part of his vision.
The reunited 6 Avengers exit from the ant-hill, and Iron Man buries it in rubble. But none of them know that Quicksilver is inside, dying.