Long, long ago, on the hidden island of Themyscira, female warriors known as the Amazons were created by the Greek gods to protect mankind. A young girl named 'Diana' was raised to one day, become one of these warriors. Her mother, Hippolyta, has told Diana many stories about the history of their worlds.

One of which, is the exciting legend of Ares, the god of war, who saw the dark, selfish thoughts and desires of humanity, and became jealous of how much this corrupt species was blessed by Zeus' mighty hands, questioning if he would ever do the same things for the gods he rule over. In a fit of rage, Ares organized mankind's destruction, by way of offering them power, which they'd use to destroy their fellow humans, in return for doing what he says on how to do it. This caused the Romans to destroy Egypt, thieves to steal, killers to kill, and much more. Almost immediately, things started looking grim.

When the gods stood in his way, Ares took them out one-by-one, until he fought Zeus. Nearing the end of the battle, Zeus used the last of his power to wound Ares and force his retreat to Earth, never to be seen again since. Zeus only had a few more moments to live, but before dying, Zeus left the Amazons a weapon, known as the "God-killer", to prepare them for Ares' return.

Hippolyta would tell Diana that she is destined to be a great warrior, and the Amazons could always use more great warriors.

Centuries have passed, the year is 1918, and Diana is now a young woman. Nearing the end of her training, she must perform an courageous act of her own, to finally earn the title of 'warrior'. One day, a strange, aircraft lands on shore of Themyscira, and Diana saves the human pilot, who introduces himself as 'Steve Trevor', and explains that his aircraft is called a 'plane'. After this, Themyscira in invaded by an army of sinisterly-dressed humans, who were the ones who made Steve's plane crashed. Luckily, the Amazons all saw the invasion coming in the distance, and managed to suit up, and defend Themyscira in a nick of time.

In the end, the army retreats, and Diana interrogates Steve with her signature weapon, the Lasso of Hestia. Soon, Steve explains that a war has been going on in the human world, with the invaders being known as 'Germans', led by their dastardly emperor, Willhelm II. The Germans were chasing Steve because he was a spy for an union of nations known as the 'Allies', who are the ones trying to stop the Germans from taking over the human world. However, the Germans are winning, and the war is getting darker by the minute.

Diana considers all the disasters her mother described when telling her about Ares, and thinks that he might be behind this war. After thinking about all this, Diana goes to the chiefs of the Amazons, and asks permission to go to the human world, and take the god-killer with her. After much consideration and debate, she convinces them to let her take it.

Steve fixes his plane, and takes Diana to London. Along the way, they have a conversation that happens like this:

DIANA: So, what exactly did you do while spying on the Germans?

STEVE: I stole a notebook from their labs, where they create these chemicals for war.

DIANA: Chemicals? What's a chemical?

STEVE: It's a substance that, um, has been changed for, um, a specific purpose.

DIANA: Kind of like potions?

STEVE: *shrugs* Yeah, I guess you could say that.

DIANA: So, who did the notebook belong to?

STEVE: One of their chief chemists, but I never learned the name. Apparently, their trying to create a deadlier form of poison gas.

DIANA: And what is this poison gas?

STEVE: Well, uh, it's like this, uh, green cloud, where if you breath in this green could, it could kill you in a matter of minutes, or less.

DIANA: I see, no wonder they wanted this information back.

STEVE: That's what I was thinking right before I crashed on your island. Speaking of which, what makes you so sure that this 'Ares' guy is responsible for the war?

DIANA: You wouldn't know unless you heard the story.

STEVE: Well, we're a long way from our destination, so I have time.

Diana begins telling Steve the story, before the screen dissolves to the next scene, where they're in the streets of London, and Diana is in a disguise that fits the scene.

DIANA: Forgive me if I'm being rude Steve, but is this disguise really needed?

STEVE: Well, humans haven't had contact with gods for so long, that they don't believe in them anymore. So if they see you in that armor, they're gonna think you look odd.

DIANA: If you say so.

Later, they go to the Supreme War Council, to present the notes to them, and talk about what they should do.

When he they get there, Steve and Diana go before the Council, and Steve translates the notebook, noticing something he didn't before: The Germans were planning to release the deadly gas into the Western Frontier, and the deaths would be so many, Germany could possibly win the war in minutes. The Council permits Steve to put together a team, with their funding. Steve is immediately excited, considering he was never given such a duty, and tells the Council that he won't let them down.

With Diana at his side, Steve recruits Moroccan spy Sameer, Scottish marksman Charlie, and Native American smuggler Napi to help prevent the gas from being released. Steve takes Diana, and the team to No Man's Land, but on the way, one of them asks why a woman is coming with them, and Steve tells them that she's with him, but slightly closer. This leads to some of them making fun of them, and joking about them being in a relationship.

Later, in the trenches of No Man's Land, Diana and Steve get separated in the crossfire of the battle. The commander tells the team that the battle is already lost, and they must fall back, but Diana sees all the chaos, death, and destruction around her, and refuses. Instead, she rises above the trenches, where she removes her disguise, showing the Amazon armor underneath. The camera moves in front of her, showing her march into battle, as explosions happen all around her. The Germans see her, and are confused as to why the U.S military would send a woman in strange armor to fight, but start shooting at her anyway.

Diana blocks the bullets with her bracelets, but when the heat started to really come in, she used her shield to block them, before saying to the American soldiers, "What are you waiting for?! Come one!"

The commander than says, "Alright, men! You heard the lady, give her a hand!"

Then, the Americans go into battle, and with Diana leading, the Allies won the battle, and even liberated a nearby village. The team briefly celebrates, taking a photograph in the village, where Diana and Steve fall in love.

We then cut to a montage of Diana fighting with her team in several different WWI battles. Eventually, they're sent on a mission to a gala at the German High Command, which Germany's leader, Kaiser Wilhelm II, will be attending. Diana goes, thinking that either he, or one of his associates could be Ares.

The team goes to the gala, and alongside Wilhelm, is general Alfred von Schlieffen, the one who organized most of Germany's invasions, while Wilhelm is the one who has the army carry out those plans. Diana hears about this, and thinks that Schlieffen secretly could be Ares.

In a small matter of time, Steve notices that Diana is missing, and goes off to find her. He sees her trying to kill Schlieffen, and stops her to avoid jeopardizing his mission, but this allows Schlieffen to notice them, and get away. Blaming Steve for intervening, Diana follows Schlieffen to a base where the gas is being loaded into a bomber aircraft bound for London.

Diana forces Steve to fly her over to London, but when they get there, they see the entire city burning. Germans are everywhere, killing people left and right. Diana looks down to see Wilhelm and Schlieffen in the middle of the battle, smiling widely at the death and destruction. Then, Diana leaps off the plane to confront them, and they immediately notice her.

Wilhelm asks Schlieffen if this is the Amazon warrior the Allies have, and he confirms. Diana asks how they know she's an Amazon, and Schlieffen, out of pure cockiness, reveals himself to be Ares by removing his disguise.

Wilhelm, while talking over a flashback, then explains that when he was a young boy, all he ever wanted to do was make his parents happy, but he almost always failed at that. The only reason he wanted to make his family proud, however, is because it'll give them reason to grant him his birthright of becoming emperor. But he met Ares at the age of 8, after falling off his horse, and breaking his arm. Ares promised him all the things he could want, and more, if he did the things he said, and they made this promise that it would happen like that. As time went on, Ares took the form of many people who stood aside Wilhelm in his quest for power. Finally, Wilhelm became, not just a charismatic emperor, but a physical embodiment of power, confidence, and corruption. Until one day, when Ares talked him into ruling more than just Germany, but maybe even the entire world, hence the reason for the war itself.

Ares then said, "Don't you see, young Diana? Humans are a race that Zeus protected for no reason! He was king! He was all-powerful! He was a being everyone labeled as "wise", and he chose to waste his protective hand on these worthless, evil creatures."

Wilhelm is nodding as he speaks, but then starts a sentence with, "Hey! Wait a min-" but is cut short by Ares force-pushing him to the side.

DIANA: Well Ares, you're right, humans are selfish. But they are not collectively evil. I have seen goodness in them!

ARES: *evil laugh* Really? Where?

DIANA: In the form of Steve Trevor.

ARES: The pilot? Oh, come now. What has he done for you?

DIANA: If it wasn't for him, I wouldn't have this opportunity, this chance, to earn something I've been dreaming of having since I was a child: The Amazon title of 'warrior'.

Diana reveals that she has the god-killer, and Ares evilly laughs again.

ARES: Zeus himself could not kill me, what hope do you have with a weapon made by his hands?

DIANA: I don't need to hope, I need to try, and try is what I'll do to make sure you, and Wilhelm, are both stopped, Ares!

ARES: Well, in that case, finish me if you can!

A big fight rises, and Diana dukes it out with Ares, and destroys many things in the environment while trying to kill Ares with the god-killer sword. But at the end of the fight, Ares knocks the sword out of her hands, pins her to the ground, and is about to kill her, when suddenly, the god-killer is shot into his back, and out his chest. He sees this, and faints, revealing Wilhelm as the person who killed him. Wilhelm helps Diana up, gives her the god-killer, and tells her to help the Allied soldiers, and he'll tell the German soldiers to retreat.

DIANA: Wait! Why did you help me?

WILHELM: I don't know how, but I've never noticed his evil until now. But when I saw you putting your life on the line for a race like the humans, I saw no reason in not helping you.

Eventually, Wilhelm returned to Germany, where he signed surrender treaties, giving the Allies the victory. The team celebrates the end of the war, Diana returns home, and with Steve as a witness, tells the other Amazons what she done.

Diana is rewarded with the title she always wanted, Hippolyta tells her that she made her proud, and she promises to Steve that she'll return to the human world, when it needs her most, and Steve leave the island telling her that he'll be waiting. The final shot is with Steve flying into the sunset with his plane, while Diana gladly watches.

POST CREDIT SCENE: Diana walks up to a well, and says to herself, "Let's see what's happening in the human world." And the water in the well give her an image of Joker, dancing on the rooftop of the police car, like in the Joker movie. Diana sees this, and wonders if humanity needs her again.