They enter the underground facility and are soon joined by Iron Man.

Tony: You seem a little defensive.

Rogers: It's been a long day.

Tony: [to Bucky] At ease, Soldier. I'm not currently after you.

Rogers: Then why are you here?

Tony: Could be your story's not so crazy.

Iron Man: Ross has no idea I'm here. I'd rather like to keep it that way. Otherwise, I gotta arrest myself.

Captain America: [smirks] That sounds like a lot of paperwork. . . It's good to see you, Tony.

Tony: [to Bucky] Hey, Manchurian Candidate, you're killing me. There's a truce here. You can drop . . .

Buck relaxes his guard and the three of them search the facility, unaware Black Panther is close behind. They find that the super soldiers have already been killed, and Zemo, hidden behind indestructible glass.

Captain America: You killed innocent people in Vienna just to bring us here?

Black Panther hears Zemo admit responsibility for the explosion.

Zemo: I've thought about nothing else for over a year. I studied you. I followed you. But now that you're standing here, I just realized there's a bit of green in the blue of your eyes. How nice to find a flaw.

Captain America: You're Sokovian. Is that what this is about?

Zemo: Sokovia was a failed state long before you blew it to hell. No. I'm here because I made a promise.

Captain America: You lost someone.

Zemo: I lost everyone. And so will you. An empire toppled by its enemies can rise again. But one which crumbles from within? That's dead. Forever.

Zemo reveals that his real plan was to find footage of the Winter Soldier's first mission. Zemo shows them a video of Bucky causing the car crash.

Howard Stark: Sergeant Barnes?

The video shows Bucky murdering the occupants, Howard and Maria Stark, in cold blood.

Tony: Did you know?

Rogers: I didn't know it was him.

Tony: [struggling to keep his temper] Don't bullshit me, Rogers! Did you know?

Rogers: [hesitantly] Yes.

Incensed, Iron Man attacks both Cap and Bucky. A brutal battle erupts.

Rogers: It wasn't him, Tony! Hydra had control of his mind!

Tony: Move!

Rogers: It wasn't him!

Captain America does his best to stay between Iron Man and the Winter Soldier while he tries to escape. Bucky is climbing up the silo when Iron Man aims a wrist missile at him.

Friday: Targeting systems knackered, boss.

Tony: I'm eyeballing it.

The missile blasts seals Bucky inside the silo and Tony flies up to him to engage in hand to hand combat.

Iron Man: [restraining Bucky, whispering in his ear] Do you even remember them?

Once again, Captain America comes to Bucky's defense.

Captain America: This isn't gonna change what happened.

Iron Man: I don't care. He killed my mom.

There's now a hand to hand combat with Iron Man taking on Rogers and Bucky at the same time.

Bucky is about to rip out Tony's chest piece, but Tony blasts off Bucky's metal arm, who is down and out for the count. Rogers steps in to take on Iron Man.

Meanwhile, outside the facility, Black Panther confronts Zemo.

T'Challa: Is this all you wanted? To see them rip each other apart?

Zemo: My father lived outside the city, and I thought we would be safe there. My son was excited. He could see the Iron Man from the car window. I told my wife, "Don't worry. They're fighting in the city. We're miles from harm." And the dust cleared, and the screaming stopped. It took me two days until I found their bodies. My father still holding my wife and son in his arms. And the Avengers? They went home. I knew I couldn't kill them. More powerful men than me have tried. But if I could get them to kill each other. I'm sorry about your father. He seemed a good man, with a dutiful son.

T'Challa: Vengeance has consumed you. It's consuming them. I'm done letting it consume me. Justice will come soon enough.

Zemo: Tell that to the dead.

Zemo tries to commit suicide with a gun, but Black Panther places his hand over the barrel, stopping the bullet.

T'Challa: The living are not done with you yet.

The fight continues between Iron Man and Captain America, who batters Tony relentlessly.

Friday: You can't beat him hand-to-hand.

Iron Man: Analyze his fight pattern.

Friday: Scanning. . . Countermeasures ready.

Iron Man: [blocks Cap's shield attack] Let's kick his ass!

A few Iron Man blasts later, Rogers is beaten to the ground.

Captain America: He's my friend.

Iron Man: So was I.

Iron Man pounds Rogers severely and points his blaster at Steve.

Iron Man: Stay down. Final warning.

Captain America: I can do this all day.

Iron Man is distracted by Bucky reaching for him, which gives Captain America the opportunity to launch a new offensive. Cap disables Iron Man's suit, defeating the wounded Tony for good. He then helps Bucky to recover.

Tony: That shield doesn't belong to you. You don't deserve it! My father made that shield!

Steve drops the shield and leaves with Bucky.

Sometime later, we see Zemo in glass prison module.

Everett Ross: Meals at 8 and 5. Toilet privileges twice a day. Raise your voice, zap. Touch the glass, zap. You step out of line, you deal with me. Please, step out of line. Hmm? . . . So how does it feel? To spend all that time, all that effort, and to see it fail so spectacularly?

Zemo: Did it?

Tony eventually returns to the Avengers' headquarters and helps with Rhodey's recovery. Tony has given him robotic legs to recover from paralysis. A FedEx Driver (Stan Lee cameo) appears at the door with a package.

FedEx Driver: Are you 'Tony Stank'?

Rhodes: [cracks up] Yes. This is Tony Stank. You're in the right place. Thank you for that! [to Tony] Never dropping that, by the way. Table for one, Mr. Stank. Please by the bathroom.

Alone, Tony opens the package containing a letter and a flip phone.

Rogers: [letter to Stark] Tony, I'm glad you're back at the compound. I don't like the idea of you rattling around a mansion by yourself. We all need family. The Avengers are yours, maybe more so than mine. I've been on my own since I was 18. I never really fit in anywhere, even in the army. My faith's in people, I guess. Individuals. And I'm happy to say that, for the most part, they haven't let me down. Which is why I can't let them down either.

Locks can be replaced, but maybe they shouldn't. I know I hurt you, Tony. I guess I thought by not telling you about your parents I was sparing you, but I can see now that I was really sparing myself, and I'm sorry. Hopefully one day you can understand. I wish we agreed on the Accords, I really do. I know you're doing what you believe in, and that's all any of us can do. That's all any of us should... So no matter what, I promise you, if you need us - if you need me - I'll be there.

Steve breaks the heroes out of their island prison and they go to Wakanda, where T'Challa gives them asylum. Bucky elects to be put back into cryogenic sleep until they can find a way to cure his brainwashing, so that no one will be able to manipulate him again.

Rogers: You sure about this?

Bucky: I can't trust my own mind.

Sometime later, T'Challa joins Rogers outside the cryogenic area.

T'Challa: Your friend and my father, they were both victims. If I can help one of them find peace.

Rogers: You know if they find out he's here, they'll come for him.

T'Challa: Let them try.

Peter Parker is recovering from his injuries at home, and he tries out a new version of the web shooter that Tony gave him.

May: [off-screen] Who was it? Who hit you?

Parker: Some guy... so itchy man, God.

May: [off-screen] What's "some guy's" name?

Parker: Uhh, Steve!

The webshooter emits a light; Peter is amazed.

May: [off-screen] Steve? From 12-C? With the overbite?

Parker: No, no, no, you don't know him, he's from Brooklyn.

Peter hides the webshooter light under his arm as May enters.

Parker: [feigning pain] Ouch.

May: Well, I hope you got a few good licks in.

She hands Peter an ice pack wrapped in a towel.

Parker: Yeah, I got quite a few in actually.

May: Okay.

Parker: His friend was huge, like HUGE!

He presses the ice pack to his black eye while hiding the webshooter.

Parker: That's way better, thank you.

May: Okay, tough guy.

Parker: Love you, May. Hey, can you shut the door?

May shuts Peter's door. Peter unveils the webshooter light and shines it onto his ceiling, projecting the Spider Symbol. Peter smiles.