When he was a small boy in 1926, Steve often witnessed his mother being brutally hit by his alcoholic father. No matter how hard he hit her, she would always stand back up. When Steve asked his mother why didn't she just stay down, his mother replied that getting back up was always the right thing to do. In the present, Captain America stands on top of a plane about to crash down in Manhattan. He has stabbed his shield into the plane's fuselage to avoid falling off. The plane is piloted by the Green Skull, an eco-terrorist who believes that the only way to save Earth from pollution is to destroy mankind. The plane is rigged with missiles containing Omega Fertilizer, a chemical that can cause plans to grow on people. Cap enters the cockpit and dispatches the Green Skull and his henchmen. He then aims the plane away from the population center, grabs the Green Skull and jumps off the plane with a parachute. He lands near a police officer, telling him to call the Avengers. Moments later, the plane crashes down to a river. Shortly afterwards, Cap meets up with Sharon in a lone alley. As Steve kisses her in the cheek, they change to their civilian clothes. It turns out that today, Steve is 90 years old. Walking to a subway station, Steve and Sharon enter to a secret elevator that leads to a subway car hidden within the station. According to Sharon, S.H.I.E.L.D. has been monitoring that car's activity, and that line has been abandoned for more than eighty years. Their mission is to investigate that line. However, as they arrive to the stop, the guard tells them that the car has room for only one person. Steve agrees to go and enters the car. As he travels in the car, Steve thinks about Sharon's marriage proposal. While he thinks marriage might not be a bad thing, Steve believes that he has been dedicated to his life as a soldier for too long. In that moment, the car disappears into a flash of light, entering a mysterious realm. Steve is also injected with an anesthetic. Waking up, Steve finds himself strapped into an operating table. In that moment, Arnim Zola appears before him, welcoming Steve to the Dimension Z. Alongside Steve is a baby inside a large glass tube. Zola injects Steve with a large syringe, intending to extract a sample of his blood. Steve frees himself from the table and recovers his uniform and shield. As Zola's mutates surround him, Cap jumps through a window and escapes. Zola realizes that Captain America has taken the baby with him. The boy is Zola's son. As he talks with a young girl, his daughter, Zola reveals that he wanted to extract the Super-Soldier Serum for his children. Believing Captain America has killed his son, Zola summons his mutates, telling them to bring Captain America to him. Captain America tries to escape Z Dimension on a jet, but the jet is shoot down by enemy forces. Escaping the wreckage, Captain America decides to protect Zola's son and find another way to escape.
Captain America and his young ward "Ian" are trapped in a desert like environment in Dimension Z. Cap cannot find his bearings or direction due to the chaotic nature of the stars and other phenomenon. Although things are dire, Steve has a flashback to his childhood in 1926 and is reminded of his alcoholic father who lost hope. Steve Rogers resolves not to lose hope for he and Ian. Steve is suddenly attacked by two of Arnim Zola's mutates. Steve knocks one out with is shield, but the other is about to kill him when he is suddenly bitten in half by "the Thing Beneath the Sand" a giant flesh devouring monster. The monster buries himself under the sand after his kill. However Steve and the other mutate are captured by other mysterious armored human like creatures. Ian, Steve and the Mutate are taken to the leader of these humanoids. This leader now wields Captain America's mighty shield. When the Mutate proudly states that he works for Zola, the leader of these human like creatures decapitates him with Captain America's Shield. The leader then puts Ian in a position to decapitate him as well. Steve begins pleading that neither he nor Ian are allied with Zola. The story ends with a mighty clanging sound effect taking place.
Still trapped in Dimension Z, Steven and Ian convince the alien Phrox not to execute them. The alien Ksul particularly befriends Steve despite the animosity of the tyrant leader, Zofjar. Steve stays with the Phrox recuperating his shattered hand. He thinks back to being bullied and beaten in New York City by Hutch and his gang as well as his friendship with Arnie Roth. Back in Dimension Z, Steve tells Ksul that he believes Zofjar is a tyrant and should be removed. He encourages Ksul to try to change the way the Phrox are living. Zofjar hears this conversation and begins beating Steve. When Ksul intervenes, Zofjar shoots him in the face. Steve battles Zofjar, but struggles to overpower him. Zofjar slashes Steve's midsection. Steve is able use the last of his energy and punch out Zoljar. Steve then escapes to examine his wound that should be life threatening. Instead he finds, that Arnim Zola's image and technology has been implanted into his body.
It's been eleven years since Steve was stranded in the Dimension Z. He has been training Ian in how to throw his shield properly. During the training sessions, Steve and Ian have become very close. Standing on a cliff, Steve and Ian watch Zola's army ready to mobilize. In that moment, one of Zola's creatures aims a gun at them, but Ian shoots him dead. Trying to escape the area, Steve finds a bike with a map that shows a way to return to his home. Ian is unsure about this, saying that he has no home. He asks Steve to tell him about his mother, but when Steve tries to answer, Zola's voice torments him within his mind. As Zola begins to taunt Steve about how he killed Ian's mother, Steve falls unconscious. Steve dreams of his childhood, when his mother was very sick. Steve's grandfather Ian had died last winter. The building's landlord also demanded that Mrs. Rogers pay the rent from the past two months or he would throw her and Steve out. Desperate for money to buy medicine for his money, Steve asked his friend Deirdre for a favor. Deidre introduced Steve to a group of bullies, the same ones that attacked Steve before on his way home. Hutch, the gang leader, decides to let Steve help them pull off a robbery. Steve distracts the owner of a pharmacy while the thugs throw a rock to the window. Using the distraction, Steve steals some medicine and money from the cash register. As he meets up with the thugs, Hutch allows Steve to keep some of the money, being impressed that Steve could steal. Returning home, Steve gives the medicine to his mother. She asks how did Steve got the medicine and the money, but Steve says that he will do whatever it takes to help her. However, Sarah wants to Steve to remain a good person, no matter what happens. The next day, Steve returns to the pharmacy and explains his situation to the owner. Taking pity on the boy, the owner allows Steve to work for him to pay for the damages. As Steve wakes up, Ian sees Zola's electronic face on Steve's chest. Realizing that Zola is his father, Ian asks why did Steve never told him and Steve replies that he wanted to tell him when there was no longer any hope he could hold him off. Zola has been trying to take control of Steve's body for years, but now there is a chance for them to return to Earth. When they return, Steve will get help from the Avengers so that they can help the Phrox defeat Zola's forces. Meanwhile, in Zola's fortress, a woman shows her captured foe, a Phrox, to Zola. She is Jet Black, "Princess Zola". The captured Phrox is a tribe chief exiled by Captain America. Surprised by Captain America's survival, Zola prepares his new mutate soldiers, based on Captain America. Jet Black also wants vengeance on Captain America, believing that he killed his brother.
As Steve and Ian return to the Phrox's hideout, Steve is still struggling to keep Zola from controlling his mind. Unfortunately, Zola's forces have located the Phrox's hideout and a battle has ensued. Zola and Jet Black watch the battle from afar. Hoping to lure Steve into the trap, Zola unleashes his newest creations, the Captains of Zoolandia. Steve and Ian enter the fray. Steve is impressed by Ian's valor and is also aware that Ian sees as the Phrox as family just as he sees Steve as a father. Knowing that Ian would rather die fighting for them than leaving them to their fate, Steve promises not to fail him. Then, the Captains of Zoolandia attack them. Jet Black also enters the battle, leaving her staff behind, as she wants to kill Steve with her bare hands. Believing that he killed her brother, Jet Black brutally attacks Steve, but just as she is about to deliver a killing strike, Ian incapacitates her. Realizing that Jet Black has been twisted by Zola's lies, Steve leaves her under Ian's watch while he returns to the fight. Jet Black informs her father that Ian still alive. Realizing that Steve took Ian with him instead of killing him, Zola orders the Captains of Zoolandia to pull back and attacks Steve by himself. Then, he orders Jet Black to kill him, but Jet Black, confused that Steve showed her mercy, refuses. Instead, Zola blasts Steve off a cliff, much to Ian's horror. As he takes Ian and Jet Black back to his base, Zola orders the Captains of Zoolandia to destroy the rest of Phrox clan. Ian proclaims that Steve is his father, but Zola replies that he will learn to be his son. Steve wakes up, albeit very injured. Zola's voice taunts him about his failure to protect Ian, telling that he should give up. Remembering what happened to his father, Steve refuses to give up and proclaims that he will always help those in need. He then grabs a blade and stabs himself in the chest, destroying Zola's implant. Steve then grabs his shield and promises to get his son back.
Jet Black prays to an altar dedicated to Zola, to who she worships like a god. During her prayers, Jet admits to feeling drawn to Captain America. Even though she has been taught to hate the notions of compassion and temperance, she feels confused by Cap's decision to spare her life. As she finishes her praying, Jet asks Zola for salvation. A group of Zola's mutates guard the gate to Zola's stronghold until an out-of-control flying bike crashes into the gate. Then, Steve ambushes the mutants and swiftly kills them. Steve continues into the fortress, ready to put an end to Zola once and for all. Meanwhile, Jet puts a special armor on Ian so that he begins his new education today. Ian refuses to acknowledge Zola as his father, saying that Steve is his real father. He is also confused as why Jet is so loyal to him, and she replies that Zola taught her that life is a struggle in which one must destroy or be destroyed. However, Ian says that Steve taught him that the strong must always protect the weak and never lose hope. He also feels angry at Jet for causing misery to the Phrox, a good and peaceful race. As Steve continues into Zola's fortress, he begins to think of the life he lost: he lost his friends, his responsibilities and Sharon. He lost ten years of his life. Even so, Steve refuses to let Zola keep Ian; because even though he has Zola's genes, Ian is a good person. Once he defeats Zola, Steve will give Ian the normal life he deserves. Suddenly, Steve finds dump composed of the failed mutates Zola created in Steve's image. Zola uses a Phrox test subject to create a perfect Captain America clone so that he can infiltrate Earth. Suddenly, one of Zola's servants tell him that Captain America has entered Zoolandia. Zola's experiment also fails and the Phrox is left disfigured. As Zola throws the failed test subject into the body dump, he decides to continue his plans to create a family. Meanwhile, Steve has reached the tunnel that brought him to Dimension Zola. Steve briefly considers returning to Earth and getting help from the Avengers, but he cannot leave Ian to his fate just like his own father did many years ago. Steve crawls into the waste tunnels in order to infiltrate the fortress. Zola orders his forces to destroy Captain America while Jet brings Ian to him in order to begin his teachings. Ian still refuses to believe Zola is his father, but Zola wants Ian to be his heir. He says that his mother, Mary, wanted to call him "Leopold" but Captain America stole him from them. But now that he is back, Zola can re-educate him into being his son. Zola justifies his massacre of the Phrox as a weaker species by a stronger species in evolution. He then places Ian in his share, showing pictures of Captain America in World War II. As Zola watches footage of Bucky, Zola compares him to Ian on how Captain America raised them to fight and kill. Steve ambushes Jet in the showe with a gun, asking about Ian. Jet refuses to let Ian go with him, saying that Steve kidnapped him and stole him from his father. However, Steve doesn't want to let Ian get brainwashed by Zola and asks about his location one more time. Jet refuses to answer and Steve pulls the trigger. Meanwhile, Zola has finished re-educating Ian, who says that Zola is his true god.
Two years ago, Steve and Ian were having lunch were the Phrox were harvesting food. Ian asked Steve if he missed his life back on Earth and Steve said that he was happy enough with him. Steve also tells Ian about his father and about how he left his family because he lost hope. Steve has attempted to make not to make the same mistakes his father did and chose not to abandon Ian and always be there for him. In the present, Steve has infiltrated Tower Zolandia in an attempt to rescue Ian. He also spared Jet, instead, he leaves tied up in her room. Jet informs the situation to her father, who decides not to take any chances with Steve in his fortress and activates his plan. After defeating Captain Zolandia, Steve moves to another part of the tower and encounters Jet again. As the two come to blows, Steve attempts to convince her to help him save Ian and the Phrox. During the fight, a Phrox female is thrown to a lava pit. Steve tries to save her and asks Jet to help him, appealing to her inner goodness. Surprising even herself, Jet decides to help Steve save the female. Jet reveals the truth behind Zolandia: the entire tower is in fact a massive battleship that will invade Earth and conquer mankind. Steve and Jet agree to work together to stop Zola. While Jet goes to help the Phrox, Steve attempts to get to Ian. In that moment, Ian, fully brainwashed by Zola, shoots Steve in the back.
Ian has shot Steve Rogers. Captain Zolandia, one of Zola's' mutates, wakes Steve to beat and torture him some more. He tells Steve that he has his memories and that he knows that Steve Rogers is really the person who killed his mother and that his cause is misguided. Steve impales Captain Zolandia with his shield. Ian then attacks Cap again. Steve eventually punches him and runs off. Meanwhile, Zola prepares his mutate army to attack the earth. However, Jet Black has turned on her father. Jet releases the Phrox prisoners and prepares to stop her fathers plan. Zola intercepts her and the two prepare to battle. Ian impales Steve form behind with Captain Zolandia's shield and puts a pistol to Steve's head. Steve urges Ian to make his own decision. Choose to be his son rather than Zola. Steve tells that he chose to be nothing like his biological father and that Ian can too. Ian appears to unravel from Zola's brainwashing. Suddenly, Ian is shoot through the neck from behind. He falls into an abyss below.
Cap remembers his now dead "son" Ian. He tells Sharon Carter, who came to his rescue last issue, that he had raised Ian for years. Sharon insists that Steve has not been gone very long, around 30 minutes, since they parted company in Captain America Vol 7, #1. Sharon insists that this is one of Zola's mind games. Sharon has also rigged Zolandia to detonate. At first, Steve says he will not leave. Sharon urges him to "Stand Up" the same phrase his mother used to him as a child. Steve does rise up, but insists that there is someone here he still might save. In another part of Zolandia, Jet Black is fighting her father. She is losing until Cap arrives and intervenes. Jet Black jettisons and frees the Phrox prisoners of Zola. Zola is impaled and savaged by Cap and finally on the verge of destruction and complete shut down. As he "dies" he tells Jet Black that he is proud of his daughter and urges her to continue his work. Zola expires as the issue ends.
Sharon Carter is prepared to leave Dimension Z and return to earth. She tells Jet and Cap that she will detonate Dimension Z as they leave so that Zola's mutates will not invade and infest the earth. Jet Black, still reeling from her father, Zola's, apparent death, is outraged. She punches Sharon, steals her detonator, and races off on a sky sled. Cap and Sharon give chase. Soon Zola's mutates, led the Captain America mutate, pursue them. Cap falls off Sharon's sky sled and defeats the Captain America mutate. Sharon convinces Jet to return with the detonator. Captain America is also plunging from his sky sled which crashed with his mutate foe. Jet Black catches him and the two ride on the sled. As the group again plans to leave, a larger more deadlier Zola appears. Zola tells his daughter, Jet, that she has failed him again. He shoots deadly eye beams. Sharon almost falls to her death but Captain America grabs her hand. Sharon then tells Steve that she has a plan that they can still detonate Dimension Z and return safely to earth. She slips from Cap's grasp, telling him that she loves him. She lands on the giant Zola and shoots him to death. Cap urges Jet to take their sky sled, but it is too late. Jet and Cap return back to 51st Street in New York. Steve is visibly upset, crying over his loss of Sharon. Back in Dimension Z, some of Zola's mutates remain and continue to terrorize the world, but they are besieged by a "Ghost Warrior", a "Nomad". This Nomad of Dimension Z is Cap's son Ian.