Synopsis
Iron Man is sitting on a rooftop edge eating a takeaway burger while Dr Strange is sitting in midair near him eating takeaway chow mein. Tony Stark asks Stephen Strange if he can see what he sees. Stephen mentions mating phantom squids, a dying gargoyle, and a werewolf and 2 Dark Elves sharing a forbidden kiss but none of these are what Tony meant. But since the populace of Greenwich Village aren't running away screaming Tony guesses nobody but him can see it.
Over the following days Stark ascertains that Brother Voodoo, Moon Knight and Spider-Man can't see or sense anything. But eventually Strange agrees to do a magic investigation. And we finally see a giant tentacled monster with a keyhole symbol on its head, in chains above Dr Strange's Sanctum Sanctorum.
Later they're in a SHIELD Helicarrier over the Arctic Sea and outside Tony Stark, new Director Of SHIELD says he now sees a *really* huge humanoid with multiple eyes and his neck in chains, also with a keyhole symbol on its brow. They banter about Tony's dubious mental state and a possible bondage fetish. Strange takes a blood sample from Stark's thumb which the Helicarrier's AI, which Tony Calls DEEDEE, interprets as an attack until he uses his authorisation to allow Strange freedom of the place. And they enter a hall of wonders which includes the Iron Spider armour that Tony created for Spider-Man (during Civil War). Stephen spots Hulkbuster and Thorbuster armours, and asks why Tony has prepared contingency plans against his allies but hasn't created, say, a Thanosbuster armour. He wonders if this is connected to why Tony is seeing monsters all around him. Anyway DrS has used Stark's blood to create mystic eye-drops which will enable him to see what Tony sees.
Our next scene is in the Yaba district of Lagos City where SHIELD is investigating a strange death. Maria Hill is there and she's called in Iron Man. Apparently the victim had been acting paranoid and stopped coming to work or seeing anyone 3 weeks ago. It is assumed he died then but he was an alien with a healing factor which makes it difficult to be sure. The killer removed vital organs to ensure he stayed dead. Stark suggest they could regrow organs for him and then his healing factor could bring him back to life. Hill points out that his brain is missing.
Maria takes Tony aside to explain why she involved him. This is the 5th similar murder in 2 months of extraterrestrial immigrants granted legal status by SHIELD and personally assigned residence/work by *him*. Many in SHIELD suspect his hand in their deaths and she wants to hear his side of things. She shows him a room where the victim has written Iron Man all over the walls. But Tony also notices a large keyhole symbol on the wall too, and remembers such symbols on his vision monsters.
Next IM and Hill are in a SHIELD submarine (with trailing jellyfish-like appendages). Hill is keeping a big gun trained on Stark as he speaks an explanation that they're heading to stop another murder of an extraterrestrial processed by himself. As agreed he's repeating this every half hour of their 2 hour journey to reassure Maria that he's still Tony and hasn't been taken over by the killer. However Tony points out that the if the killer can possess him then it could access his memories and fool her. She counters that by pointing out that her big gun suits all situations.
We see another giant chained keyhole demon looming over their destination Atlantis. Our duo get there but they have to contend with immigration bureaucracy to see the target, and by the time they get there the murder has been done. Hill wants to follow SHIELD procedures and have Atlantis go into lockdown because the killer is probably still there, but her Director says they haven't time to deal with Atlantean bureaucracy again. He knows where the last surviving immigrants are and he prefers to save *them* rather than catch the killer.
The pair return to their sub, which is also controlled by DEEDEE, and shoot up out of the Atlantic Ocean. The sub's appendages turn out to provide rocket power, and the craft turns out to be spaceworthy. So soon they're in the oxygen atmosphere of the Blue Area Of The Moon. When they exit their craft Tony confirms to Maria that only *he* knows where the immigrants are. And he tells DEEDEE to self-destruct the vehicle, which is what happens.
Hill believes she's now trapped on the Moon with Stark who is the killer, so she aims her (different) big gun at him. But he tells her that that the deaths of all the victims were spread out in time, with plenty of time for a single killer to move from 1 to the other. But the only way to get from Lagos to Atlantis was to hitch a ride with *them*. And the most reasonable way to get to the Moon was also with them. On cue an alien bursts out of the smoking ruins of the spacecraft. And Tony and Maria blast it to death.
Then Dr Strange joins them via a gateway spell to tell them he's figured out what's going on. Tony was infected by a mystic virus called The Key which finds things you have a strong emotional attachment to (which doesn't really explain why it chose alien immigrants) and then The Lock destroys them until you catch it and angrily kill it. The Lock *wanted* to be killed because this opens a lock and lets the chained monsters free and loose on Earth. And we see the monsters on a rampage.
Tony 'wonders' how he caught this mystic infection. Stephen pretends not to know what he means. Maria reminds him that the 2 of them have regular bro lunches. Strange ignores that and suggests they alert the Avengers to the invasion, but Tony says most of them don't like him at the moment. And he asks Stephen if he's still infected with The Key. And we see DrS looking like an evil version.
We also see that Iron Man is standing in front of a large building called DOME (Destroyer Of Mystic Energy) with a large 'cannon' aimed at Earth. Somehow IM and a stranger-than-usual alien (presumably 1 of the immigrants) persuade/force Strange (still dressed evil) to mystically extract The Key from Stark and deposit it in a machine inside the DOME. The alien warns him not put any of his own mystic energy in there too or he'll regret it. The alien then explains that the cannon will use the total power of a Cosmic Cube to project a beam of energy that is the antithesis of the mystic sample provided. And we see the beam obliterating the invading monsters.
Stephen looks at his friend Tony and summarises the situation. This is a weapon that uses a Cosmic Cube to cancel specific mystic energy. If a sample of *his* energy was put inside it would cancel *him*. This is Stark's Strangebuster. Tony doesn't reply and Strange (*still* dressed evil!) departs whence he came. The alien asks if they should destroy the weapon. Tony reluctantly says "No".