In Captain America Reborn, As the machinations of the Red Skull continue despite the intervention of the new Captain America, Black Widow and the Falcon, he and Arnim Zola reveal to an astonished Norman Osborn that the gun Sharon Carter used to kill Steve Rogers actually froze him in space and time at the moment of his death. That moment of spatial and temporal stasis could be used to bring back his body from any moment in the future via a modified version of Dr. Doom's time device and Sharon Carter herself, whom they referred to as "the constant."
At the time of the intended retrieval, Sharon's actions disrupted the process, resulting in Steve being lost in time and space. He is shown reliving moments of his past, most notably events during the Second World War, badly disoriented and bewildered. While going through the time stream, Steve finds himself back in 1944, at one of the Red Skull's bases, fighting Master Man. As he begins to fight Master Man, Cap figures out that he has somehow been sent back in time and reliving all of the battles he has fought in over the years. After he defeats Master Man, Steve is then sent to the time he met with President Franklin Roosevelt at the White House.
Back in the present, Bucky and Black Widow begin to fight Ares and Venom inside a H.A.M.M.E.R.Heli-carrier, but Bucky and Black Widow are defeated and taken to Norman Osborn. At the Baxter Building, Hank had brought Sharon Carter to Reed Richards, so that he could examine her. While Reed does this, Hank mentions that Falcon and the Vision are out looking for Bucky and Black Widow, since they never returned from their mission. Reed then tells Hank that he has found something in Sharon's blood stream, Reed then mentions that there was something similar to what's in Sharon's blood, in Steve's body that Reed had found after he had done an autopsy on it. Reed then tells Hank that there was something Tony Stark didn't like about the rapid cellular decay in Steve's body.
Norman then meets with Crossbones and Sin, telling them that he knows about the second shooter and that he would love to have a Captain America on his side, leading his Avengers, even if the Red Skull's mind was in that Captain America's body.
Back in the past, Steve finds himself back in 1940 with Dr. Erskine, Steve then begins to ask the doctor about time travel and what would happen if someone were to go back and kill Hitler before all of this madness began. Dr. Erskine then tells Steve that doing something like that would have both an action and reaction that could end up making it so that your loved ones might have never been born. After this, Steve is taken into a lab and is about to relive the moment he became Captain America, Steve knows that the doctor is going to be killed by a Nazi spy, but is forced to do nothing but go through with the experiment. After he does, the doctor is killed and Steve begins to ask himself why he is reliving all of his past memories.
Back at the H.A.M.M.E.R. Heli-carrier, Norman is talking to the now captured Bucky and Black Widow, Norman then reveals that he had told the whole world that Sharon Carter was the second shooter in the assassination of Captain America and is now the world's most wanted. Norman then tells them that he is letting Black Widow go so that she could tell Sharon that if she doesn't turn herself in within twenty-four hours, Norman will kill Bucky.
Still trapped in time, Steve relives the time he was trapped in the ice, he begins to wonder why he even keeps track of the time anymore, since he believes time has no meaning for him now. As he ponders on this, Namor appears, as Steve knew he would, picking up the large chunk of ice that holds Steve. Everything happens like it always did, Namor throws the piece of ice into the water, even though Steve tries to yell Namor's name, to where Steve would be found by the Avengers.
Back in the present, Reed Richards has met with Namor in the Arctic Ocean, where Steve's body was secretly laid to rest. Reed asks Namor to raise Steve's coffin, which Namor had already done, and as Reed examines Steve's body, the body disappears, shocking both Reed and Namor. As Reed tried to figure out what happened, he gets a call from Hank Pym, who tells Reed that Norman Osborn has outed Sharon Carter as the second shooter who killed Captain America, and to Black Widow's disapproval, Sharon tells them that she's going to turn herself in.
Elsewhere, Bucky is being transported by Norman's Thunderbolts, while Sharon tries to figure out what she should do. Back in time, Steve finds himself reliving his time during the Kree-Skrull War, fighting alongside Clint Barton, who was going by Goliath at the time, fighting off an army of Skrull soldiers. Steve watches Iron Man, Thor, and Captain Marvel, Steve then asks the Vision, who had asked him to meet with the other Avengers on the command deck, if the Vision could remember something and then store it deep in his memory storage, something Vision said he would have no problem doing.
Back with Bucky, Falcon attacks the Thunderbolts' jet, fighting off the Thunderbolts, while the Thunderbolts' Ant-Man frees Bucky, after that Bucky and Falcon escape unharmed.
Still jumping through time, Steve finds himself reliving the time he and Rick Jones, who was going by the name of Bucky at the time, fight off a group of HYDRA agents. Steve then feels the remorse of losing the original Bucky, his close friend James Barnes, when he almost calls Rick "Bucky". Back in the present, Norman Osborn has announced that Sharon Carter, Steve's lover, was the second shooter in his death. While he does this, Sharon is being taken to Latveria. At the Infinite Avengers Mansion, Hank Pym and Mr. Fantastic activate the message Steve left with the Vision back during the Kree-Skrull War, telling them that he is lost in time. Elsewhere, Bucky, Black Widow, and Clint Barton (Ronin), attack a H.A.M.M.E.R. mobile data-collector, trying to find out where Sharon Carter is.
Once in Latveria, Sharon is shocked to see that the Red Skull is alive still, and is with Dr. Doom. They quickly then attach her to a machine that will bring Steve back to the present. In the English Channel Islands, 1945, Steve finds himself and Bucky escaping Baron Zemo's fortress. Bucky and Steve then jump onto the drone bomber that will explode, sending them to their apparent deaths, only to live to become how they are today. Steve, who has relived this day so many times in his mind, and nightmares, decides that he won't let Bucky get blown up again and become the Winter Soldier. As he tries to stop Bucky, Steve is suddenly pulled back through time, he then finds himself being attacked by the Red Skull as he flies through time.
Steve's body then appears in Dr. Doom's lab, but as Sharon calls out to him, it is revealed that the Red Skull has placed his mind in Steve's body, and is now in control of Captain America.
Steve then finds himself in a nightmarish world ruled by the Nazis and the Red Skull. The Red Skull, who is now on his way to the White House to meet with the President to ruin Captain America and what he stands for once and for all. But as they make their way to D. C., the Skull captures the Vision who is trying to sneak on board to rescue Sharon, and commands his ship to attack the Avengers Quinjet which is chasing after them. The A.I.M. ship takes out the Quinjet, causing it to crash in front of the Lincoln Memorial.
The Avengers are forced to fight the Skull's forces. While that happens, Steve finds where the Skull is hiding in his mind, and they begin to fight over control of Steve's body. Meanwhile, Bucky fights the Red Skull outside of Steve's body. But Bucky shows that he can't kill Steve, even if it is the Red Skull controlling him. The Red Skull then takes Bucky's shield, stating that what's Captain America without his shield. He then cuts off Bucky's bionic hand, saying that it's time for a new morning in America. But before Red Skull can kill Bucky, Steve is able to force the Skull out of his mind and back into his robotic body, gaining control over his body again, and finally returning to the world he left. Sharon Carter then uses one of Hank Pym's size changer devices to make the Red Skull into a giant, making sure he can't escape this time, Steve and Bucky then team up with the rest of the Avengers, fighting the giant Red Skull, and finally are able to seemingly kill the Red Skull. As they do so, the public sees Steve among the heroes, and yell with joy as they see that Captain America has returned.
Back in New York, Steve remembers that he saw the future while he was going through time, and that he believes Bucky is going to die, but before he can think about it more, Sharon comes to get him to come down to his party.
Four days after his return, Steve had been training with Bucky, getting back into shape. He talks to Sharon, telling her how he's worried that he may slip away back into time again, she then tells him that he's not going anywhere and that she has him. Later that night, Steve decides to suit up and go out into the city, to see what has changed. He finds Captain America (Bucky) and Black Widow as they fight the Hyde who has escaped from The Raft. As Hyde tries to escape from the battle, Bucky sees Steve watching from the sidelines and throws him his shield, allowing him to defeat Hyde all by himself. Steve then says that was fun and hands Bucky the shield, but Bucky refuses telling Steve that he's Captain America and that's his shield.
Steve then tells Bucky that they need to talk. Steve tells Bucky that he should keep being Captain America, that it means something more to him, which Bucky disagrees with, saying that Steve is the only Captain America. Steve then tells him that he's not sure if he's ready or will ever be able to pick up his shield again, and asks Bucky to continue being Captain America, if not for himself, then for him.
Steve then returns to Sharon, telling her that he believes that if Bucky doesn't continue to be Captain America, that he may die, and Steve could never live with that possibility, even if it means giving up the future he wants. Steve then meets with President Obama, who gives Steve a Presidential Pardon for what he did during the Civil War, saying that he felt the S.H.R.A. was unamerican to him. Steve then tells the President that he may not be able to pick up his shield again, President Obama then tells Steve that that is okay, that he has a feeling that in the coming days, America is going to call on Steve for something much bigger.