Billionaire engineer and egomaniac Tony Stark gets captured by a terrorist organization in Afghanistan who then, with the help of the fellow captive Dr. Yinsen, builds an arc reactor to power an electromagnet to power a technologically advanced suit that allows him to become the superhero Iron Man.

Dr. Bruce Banner (Edward Norton in this movie) gets accidentally exposed to gamma rays which cause a mutation that turns him into a green monster known as the Hulk in an origin story that nobody recognizes in the MCU canon.

Stark struggles, so he gets help from his personal assistant who's actually a badass superhero Natasha Romanoff/Black Widow and best friend Lieutenant Colonel James Rhodes a.k.a. Rhodey to defeat villain Ivan Vanko.

The king of Asgard, Odin, banishes his son Thor to New Mexico where Thor meets astrophysicist Dr. Jane Foster and falls in love, while up in Asgard Loki finds out that he was adopted and tries to prove himself to Odin, but after Thor returns, Loki fakes his death... for the first time.

Steve Rogers is chosen to receive a super soldier treatment invented during World Wart II which changes him into a superhero who then discovers The Red Skull, a villain running terrorist organization Hydra, who he destroys before discovering his old friend James "Bucky" Barnes (RIP) then getting into an accident that he wakes up from 70 years later.

Captain America, Iron Man, Black Widow, Hawkeye, the Hulk and Thor join forces to defend New York City, where Loki uses the Tesseract to create a wormhole letting in the malevolent Chitauri aliens, and unified as the Avengers after Coulson's death, they prevail.

A malfunctioning treatment for injured soldiers called Extremis threatens Pepper Potts and the Vice President, but when Pepper saves herself, Stark promises to stop being a superhero, which only lasts for the next two movies that he happens to not be in.

Thor brings Jane to Asgard to prevent a virus called Aether from killing her, but an alien force invades and Thor's mom Frigga sacrifices herself to save Jane, inspiring Thor and Loki join together to release the Aether before Loki fakes his death... for the second time.

Cap, Black Widow, and Sam Wilson, a.k.a. Falcon, embark on a mission to stop a new Hydra villain called the Winter Soldier, who turns out to be a brainwashed Bucky Barnes, who Mr. Dependable, Steve Rogers, just can't give up on.

Half-human (and fully-confident) Peter Quill steals a mysterious orb from a Kree alien named Ronan who sends his evil friend Thanos's daughter Gamora to kill Peter, but instead she ends up joining him along with bounty hunters Rocket Raccoon and a tree-creature called Groot, as well as the exceedingly literal Drax and forming the Guardians of the Galaxy, who defeat Ronan after discovering that the orb holds an Infinity Stone.

Superhuman twins Pietro and Wanda Maximoff turn against the artificial intelligence humanoid Ultra, choosing instead to help the Avengers battle Ultron's army in Sokovia, resulting in Pietro's death and the city's destruction, while Tony uses Ultra's mind-powering Infinity Stone to create a new AI being called Vision, because the dude loves science.

After frequent thief Scott Lang burglarizes scientist Hank Pym, Pym instructs him to steal a size-shifting suit called the Yellowjacket, which the vengeful scientist Darren Cross plans to sell to Hydra, unbeknownst to his partner Hope van Dyne, Pym's daughter.

After the Avengers caused the destruction of Sokovia, the U.N. announce the Sokovia Accords, dividing the Avengers and causing them to fight against each other after Steve Rogers assembles a team to help Bucky Barnes release the other brainwashed Winter Soldiers, resulting in an intense battle between Stark and Rogers which still fails to fully release the pent up aggression that they've amassed over the years.

Neurosurgeon Stephen Strange visits a master sorcerer called the Ancient One who trains him to visit other dimensions on the astral plane, but Dr. Strange breaks the rules and uses the Eye of Agamotto to bend time which saves the earth from a dark sorcerer Dormammu after the Ancient One is killed.

Peter Quill learns more about his father's celestial powers from a god-like being aptly called Ego, but Ego is his father and not a great one, so all the Guardians — including Baby Groot — unite to kill him.

High schooler Peter Parker becomes more dedicated to his superhero abilities, aided by Tony Stark, and he and pal Ned uncover an evil plot formulated against the Avengers by a disgruntled city salvage employee, which results in Tony offering Peter a full-time position with the team that he declines.

Ragnarök is imminent after Odin's death releases his first-born, Hela, from imprisonment, and when Hela arrives on Asgard she sends Thor and Loki to garbage planet Sakaar, ruled by an unsettlingly attractive Grandmaster, where Thor finds Hulk and the drunken Valkyrie who escape with him, almost leaving Loki behind to die... for a third time.

T'Challa becomes the superhero leader of Wakanda, charged to protect the hidden country's invaluable vibranium against the villain Killmonger, who kills T'Challa to become the leader, but with the help of genius sister Shuri, friend Nakia, and the Dora Milaje, T'Challa is brought back into power and Killmonger is defeated.

The all-powerful villain Thanos collects Infinity Stones in a plan to destroy half of the earth's population, which comes to a head in a massive battle in Wakanda that he wins, leaving only the original Avengers and a few others as survivors.

The Wasp, and Hank Pym kidnap Scott Lang during his post-Civil War house arrest to join them in building a quantum tunnel in order to find Pym's wife Janet, but everyone but Scott is dusted in a post-credits scene, leaving Scott stranded back in the Quantum Realm.

Kree soldier Vers crashlands on Earth and teams up with young S.H.I.E.L.D. agent Nick Fury, who accompanies her in revisiting her past and discovering her true identity as Carol Danvers/Captain Marvel, the most powerful superhero ever who will most likely save the day in Endgame.

It's so fitting that the most recent MCU movie took fans back to the beginning of it all — at least as far back as the Avengers goes. And now you know all the basics you need to fully enjoy Endgame.