After searching through various realities for the missing Cable, Deadpool lands on the House of M-Earth and finds an infant Cable. He also finds the baby’s guardian, Mr. Sinister.
Wade attacks Sinister at once, while shouting details about Sinister’s life at him: “You’re an inhuman monster! Over a hundred years old, with complete control over your cellular structure! You’re a mad scientist!” etc… He then wonders why he’s shouting. The pitchfork, Deadpool’s sole weapon, enters Sinister’s arm but, due to the latter’s shapeshifting, doesn’t do any damage. Sinister replies that he has no idea why Deadpool is shouting, but that all those things are untrue... except for the complete control over his cellular structure. Sinister proves this by lengthening his arm across the room and grabbing Deadpool. All Deadpool can think off is that he should introduce this cellular structure to the Olsen Twins.
While Sinister chokes Deadpool, Deadpool sees Dazzler on the television. Sinister is surprised that Deadpool doesn’t recognize Alison, who is an A-list celebrity in the world and tells Deadpool that he would have to be a hermit or an idiot not to know her. Deadpool admits that he is an idiot. Sinister asks Deadpool what he called the baby again… Cable? Deadpool tells him that his actual name is Nathan. Sinister, intrigued, releases Deadpool and asks Nathan’s surname. Deadpool tells him that is a bit hyphenated and asks if he can use the bathroom, because he hasn’t gone in four days. Sinister tells him that it’s down the hall, first door on the right. Deadpool tells Sinister that he’s the best mad scientist ever.
While Deadpool uses the bathroom, Sinister asks questions at the door. He tells Sinister his name and tries to describe his relationship with Cable. He tells him that Cable disappeared battle the Skornn. Sinister asks about this “Scorn” but Deadpool corrects him: it’s with a K and two N’s. Sinister wonders why, though Deadpool replies that some things you just don’t question. The sound of Deadpool urinating is heard from behind the door for several minutes while Sinister waits outside. When he thinks that Deadpool is finished, the sound starts again.
Again several minutes later, the sound stops. Sinister resumes his questioning asking about Deadpool’s search. Deadpool tells him about the link between Cable and him and how Forge built a harness for him. Sinister tells Deadpool to wash his hands when he leaves the bathroom. While washing his hands, Deadpool tells about the former worlds he visited and how each world only seems to hold a piece of his version of Cable.
Sinister wants to know why he wants to find Cable so badly. Deadpool remains silent, deciding not to tell him that he wants to kill Cable. He tells Sinister that Cable was an important man. Sinister asks what kind of man: a leader (yes), a powerful man (yes), a warrior (yes), a savior (a wannabe according to Deadpool). Deadpool tells him that he’s not alone in his search.
Outside, Cannonball and Siryn are hiding behind some cows, while Terry uses her powers in a new way: she bends soundwaves, so they can listen in on Sinister and Deadpool. Sam wonders what they should do now. Siryn reminds him that, while it’s an alternate world, it still is Sinister and they shouldn’t charge in without a plan. Sam wonders what they could do; neither of them are stealth fighters. Siryn suggests checking out the perimeter first, but a large projection of Sinister appears and invites them to a barbecue instead.
At the barbecue, Deadpool is admiring the genetically mutated chicken. Sam thanks Sinister for the food, though Sinister is just happy to have guests. When Siryn wonders aloud how Sinister got the baby, Sinister tells them that, while he feels a familial bond to the child, he made him the old-fashioned way. Deadpool thinks he knocked up a local farmgirl, but Sinister’s definition of old-fashioned means combining genetic materials from here and there.
Siryn asks if Cable is a clone. Sinister replies that he’s a by-product of in vitro fertilization and very careful genome mapping. Sam wonders why. Sinister explains that the world has achieved a level of mutagenic evolution far faster than he had predicted and that he’s troubled that his theories were incorrect. Deadpool just enjoys that the mutated chickens have six drumsticks a chicken.
Sinister tells them that, after Magnus took over the world, the mutants flourished. Magnus and his children now rule the world, allowing humans to live as long as they respect the superiority of the mutants. He asks them about their world. Sam says that the human/mutant problems are still ongoing. Deadpool tells Sinister that humans hate and fear them. Sam reminds Deadpool again that he’s not a mutant. Sinister corrects Sam; he thinks Deadpool is. Both Deadpool and Sam are surprised. Sinister explains that a normal human could never have eaten so much of Sinister’s drugged food and still be conscious. Deadpool admits that he found the taste a bit tangy.
Sam and Terry stand up, ready to fight. Sinister tells them that he just wanted to drug them so he could study them. Siryn reminds him of some Irish mutant, but he is male. And Sam just seems charged with power. He hopes that they later will volunteer for an examination. Terry is less than pleased at the prospect. Deadpool enjoys the food so much that he offers Sinister to examine him and explains about his healing factor. Sinister is fascinated and tells him that he would be interested in dissecting him later. Deadpool is fine with that.
Sinister wants to show them the lab and walks in front. Sam hits Deadpool for being so stupid, but Siryn uses her powers quickly so Sinister can hear them. Wade tells Sam not to do that again unless he wants to have his own hand up his colon. He thinks that Terry’s trick with the sound is very neat and tells the two that they won’t leave until he thinks of a way to get Cable away from the “Lurch-wannabe.”
Sam is confused. Deadpool says that he’s not leaving the baby with a mutant version of Mengele and asks Sam if Mengele is too obscure a reference for the current generation. Sam tells him he knows who Mengele is. Deadpool tells them that he will distract Sinister while the other two take care of the baby. Siryn cuts the sound-shield. Sinister is lecturing them about the genetics, not noticing that they didn’t listen to him so far.
Inside his lab, Sinister has windows to all kinds of locations on the world. He explains that they are tesseract conduits that allow instantaneous transportation to anywhere on the planet. Sam wonders if they can see Westchester, he’s interested what it would look like in this world. Deadpool thinks to himself that he really wants to think Sinister is sincere but, looking around him, he’s constantly reminded what Sinister is about. Deadpool uses the conduits to learn a bit more about this world and what it would mean for the future of baby Cable if he would grow up there.
Sinister shows them a window to Westchester, warning them that they can travel through it, but traveling back is a problem. Deadpool tells them that they should call him if they’re in trouble. Otherwise, when he ports out, they will be 3 minutes behind. Sam and Terry leave.
Sinister sees that Deadpool wants to take the child and Deadpool wants a good reason why he shouldn’t. Sinister points out that Deadpool has no weapons. Deadpool replies that he has seen every Jackie Chan movie and Hi-Karate commercial ever. Sinister also points out that he wishes the child no harm. He fully intends the child to one day be the savior of this world. Deadpool just doesn’t trust Sinister as a father. Sinister says that history will be his tutor. When Magnus dies, his children will inherit control and at least somebody will try to overthrow them. The humans will rise up again if they are not extinct by then and without a savior like Nate the world will be consumed in war.
Wade asks if Sinister was waiting for Cable to grow up for this. Sinister admits that that was the original plan, but Deadpool’s presence provides a different way. An automatic syringe stabs Deadpool in the back, while machines restrain him. Sinister explains that he wants to use Deadpool’s healing factor to accelerate the child’s growth. Deadpool begs Sinister to consider how many STDs he may carry. Sinister doesn’t care and injects the healing factor into baby Nate. He looks at a monitor and tells himself how he has been marginalized in this world, while he should have led the way of forced evolution.
Deadpool warns Sinister that he’s monologuing. Deadpool changes the subject and asks Sinister if Cable displayed mutant powers so far. Sinister tells him that he has observed no powers so far, while behind him the baby levitates with an aura of psionic energy around him. The baby hits Sinister with all his raw power and Deadpool wonders why he shouldn’t let Sinister make the baby a savior. He thinks of various reasons (mostly what Cable became in the other worlds they visited), but in the end he can only think of a single reason.
Elsewhere, Terry and Sam are walking and seeing something. A flash of white light waves over them. The House of M world is changing back to the regular Earth.
Back in Sinister’s lab, Sinister is delighted to see the unlimited power that Nate has. Wade exclaims that Sinister is not allowed to shape the child’s future and crush his dreams unless he’s the child’s real parent. Little Cable will need somebody to teach him how to fire guns and love and good porn. Somebody like Deadpool.
He grabs the baby and tries to bodyslide out, but it doesn’t work. Sinister shifts his arm in a spear and stabs Deadpool. He tells Wade that, in the wrong hands, Nate could become a monster… or worse insignificant. Deadpool thinks the baby should grow up as a normal kid. Wade tries to bodyslide again and again it doesn’t work. Sinister questions normality in a world where mutants outnumber humans. Another fail attempt at bodysliding. Sinister thinks it’s the drugs he gave Deadpool and prepares to tear Deadpool to bits. Deadpool will do anything to stop Sinister from getting his hands on the kid again and, finally, he starts to disappear. Little does he know, it is the House of M world changing back, but Deadpool thinks that the bodyslide is working differently, because he now has an extra passenger: baby Nate.
Sinister sees Deadpool leaving and begs him to leave the child. His world needs it and he doesn’t know what will become of both the child and his world without him. The white light that signifies the reality change washes over all.