Synopsis
Last issue Ultron infiltrated the Infinite Mansion which gives access to the whole universe. So Wasp (Henry Pym) shut the whole system down to deny the robot villain that access. Then he, the robot Jocasta and the GRAMPA agents Ace and One-Eyed Jacquie exited into Underspace where the Mansion is physically located and we saw that it outlined the body of Janet Van Dyne, ex-Wasp and Hank's ex-wife.
Hank explains that at the end of Secret Invasion Jan was converted into an explosion of Pym Particles. He found her here in Underspace where she can continue to expand forever (as the universe does). He created the Infinite Mansion to maintain her coherence, and the 10 billion copies of Jocasta to act as neurons maintaining Jan's brain wave. He doesn't realise that Jocasta is quietly fuming at the way she's been used without her knowledge or consent (and it was all for love of Jan when the robot thought he might love *her*). But he finds out the score when she hauls back and socks him. Luckily for him he'd last issue changed her arm (and legs) to flesh versions so it only hurt a bit.
The melodrama is interrupted by the arrival of Ultron and his subverted Jocasta's. Pym is beginning to think he'd have been better off accepting Captain America's call to go defend Asgard against Norman Osborn.
Meanwhile he doesn't know that in Asgard some of the rest of the Mighty Avengers (who all quit in #34) *have* joined the battle. They are currently on a mission to stop the Thunderbolts from getting the Spear Of Odin for Osborn to use. We see some of the events in TBolts#142-143:- As Asgard begins to crumble (from the attack by Sentry) Stature stops Ant-Man from getting the Spear, and won't believe he wants to keep it from Osborn too. Nuke gets the Spear and chops off U.S. Agent's arm and leg. Vision's AI system has been crippled by the Spear. Ghost has turned against Osborn too and boosts Amadeus Cho's phone signal so he can reach Quicksilver. Pietro Maximoff is thinking of staying in his birthplace Transia. He doesn't want any more to do with the Avengers, but when he hears what's going on he speeds off to help.
In Underspace our 4 characters are on the run from Ultron and his army of 'Brides'. Henry is leading them to the monitor room where he's been working on a Pym-Wave generator which can send out an omniversal distress call. And Jocasta (the original, uncorrupted 1) contains the dimensional inducer (stored there last issue for safe-keeping) which can reopen the doors to the outside universe. But Ultron and his Brides block the way. And Ultron causes the Jan-being to speak, saying "Ultron lives!". He has reprogrammed the Jocasta-neurons so 'Jan' now serves *him*.
Hank replies that without the dimensional inducer Ultron is trapped here. And Pym will destroy it to stop him even if it means killing the real Jocasta. Ultron counters that he already sent out billions of Brides before Pym shut the doors. Henry thinks he's bluffing. He thinks Ultron kept *all* his army here because he is afraid of his 'father'. Ultron blusters that he is now Ultron Pym, the successor to Henry, and he is *not* scared of him (so there!). Wasp gets ultra-giant-size with Ultron in his hand. The robot orders all his Brides to attack him.
As *all* the Jocasta-clones concentrate on *him* Hank tells the other heroes to go to the monitor room where Jocasta will know what to do - what Janet would want. She takes Ace and Jacqui there to activate the manual kill-switch. Jacqui protests that will leave them stuck here, but Jocasta assures her she wouldn't deprive Earth of its Scientist Supreme (Henry). And Ace finds Hank's Ant-Man helmet.
Meanwhile giant Pym has led Ultron and his Jocasta's away from Jan's body. Now he switches to Wasp-size and starts to fly back. He lets Ultron know that his continuous bio-stings were jamming the robot's transmissions, allowing Jocasta to wipe the minds of her 'clones'. Now Ultron is alone. And when the Jan-body speaks to him he realises that Jocasta has done more, she's reprogrammed the body to be under *her* control. And she invites Ultron into the Mansion for a trade.
Pym lets Jocasta handle the deal as she's going beyond his plan, but he's shocked when she offers to become the robot's bride (as she was originally created to be in Avengers #162) if he agrees to go in peace. Hank reluctantly 'officiates' over the rather 1-sided ceremony where Jocasta gives Ultron complete access to her system while Ultron integrates her into his own.
This access allows him to discover that she no longer has the dimensional inducer, but it has been reconnected to the Mansion - which means the doors are open again. The dastardly villain then reneges on the deal and says he'll just go and conquer the universe as originally planned. But Henry says Ace and Jacqui have just sent out the Pym Wave to bring *all* Avengers past and present through those doors. And an eclectic group walks in through them. Faced with the assembled might Ultron caves in and accepts being stranded in a lifeless region of space. And Jocasta goes with him to keep an eye on him.
When they've gone the Avengers all disappear. It turns out Ace used the Ant-Man helmet to tell flying ants with image inducers to impersonate them. (Pym used a similar but more limited trick last issue.) But Edwin Jarvis really does step through 1 of the doors, returning from his mission to deliver an Iron Man armour to Tony Stark (see Siege #2-3). And Jocasta returns to animate 1 of the clone robots. She says she'll multitask and be here as well as with Ultron. But she won't have enough power to restart the Underspace Jan.
They open a door to Broxton where the other MAv are watching Void kill Loki (Siege #4). Wasp joins them to learn of US Agent's severe injuries. Then he leads them in the final battle against the Void.