Synopsis
As we saw in the last 2 issues, Tony Stark has left running the Resilient company to Pepper Potts, and is spending his time tinkering (this time he's invented a new(?) way of making a toasted cheese sandwich). More significantly, as we have also seen, he's moved away from the morphing Extremis-type armour to a modular form. He now explains that he can custom-make each modular unit better than the liquid-metal Extremis system could. But the downside is he has to decide what modules to incorporate before going on a mission. (Unless like last time he can take a stockpile of spare modules.)
Another thing we learned at the beginning of this run was that AIM sold Extremis technology to 4 customers (before Iron Man shut them down), after killing its inventor Maya Hansen to get it. Tony took the tech back from one customer in #2, now he's going after another. Once again Pepper asks him why he doesn't just leave it to SHIELD. His reply this time is that he owes it to Maya.
This time the Extremis signal (planted in the tech by Maya) is coming from the estate of Colombian drug boss Juan Carlos Valencia. There was a transmission from there some days ago, but it stopped. Maya's signal indicated the user died. Now there's another occurrence.
Tony plans to infiltrate Valencia's compound, and steal Extremis back. So he chooses stealth modules (including silent weaponry), leaving behind the big guns and all but limited defensive capabilities. Once again he's dressed in the armour by the new version of the JARVIS AI, which has improved its speech a lot since last issue.
Iron Man sneaks into the compound using a lightbender function to blend into the background. He overhears an exchange of passwords. Then he uses a hologram function to simulate one of the guards, and the password to get inside the house.
Maya's signal can't tell him where the Extremis tech is kept, only where the user is. So Tony homes in on that. Another function gets him through a lock, and he finds a female hospital patient. Figuring she's being experimented on against her will, he offers to help her escape. But she calls for guards.
These guards aren't just the mercenary types he passed on the way in. Valencia knew Stark was hunting Extremis users, and was prepared for Iron Man. Tony is attacked by Living Laser, followed by Firebrand and Vibro. Still sporting their specialised suits upgraded by Ezekiel Stane (with non-Extremis Stark tech) in the Mandarin storyline that occupied Iron Man's title since Fear Itself.
This version of the Iron Man armour doesn't have the raw power to defeat these 3. But gas takes out Firebrand and Vibro. Laser's photon body isn't susceptible to this. But this armour's weak repulsors are still enough to knock him down (though they'd be useless against armoured foes like Titanium Man).
Tony figures that the trio were really here protecting Extremis itself. So he tracks back the holes in walls Living Laser created on his way here, and Iron Man finds the tech he came for. And finds Valencia as well. Laser comes in for another round, but Valencia chooses instead to throw himself on Iron Man's mercy.
It turns out Juan's daughter Juliana is dying from a form of cancer that corrupts the body's repair function. But Extremis works by overwriting that repair function with one which gives selected superhuman abilities. All Valencia wants is to give his daughter back an ordinary repair function.
Valencia tried the approach on 2 patients with similar problems. One was too ill and died. The other has recovered. But Juliana is too much like the first guinea pig, and isn't doing very well.
Stark tells Valencia that Maya had an improvement to Extremis that AIM didn't get. And Tony has access to it. They do a deal. Stark cures Juliana, and gets the Extremis tech. And Valencia voluntarily goes to jail.