While every Marvel Studios movie might be a blockbuster event, Avengers: Infinity War is an especially big deal. With dozens of heroes, villains and other Marvel characters, Joe and Anthony Russo's movie is set to be a monumental turning point for the Marvel Cinematic Universe. Since Robert Downey Jr.'s Tony Stark first took flight in 2008's Iron Man, the MCU has flourished across a jaw-dropping 18 films and a host of TV series. Even for the most dedicated Marvel fans, that's a lot of characters and storylines to keep track of. With some major plot points only revealed in post-credits sequences and tie-in comic books, keeping track of the MCU can feel like a full-time job.

Luckily, CBR has a refresher on the important plot points you need to remember before seeing Avengers: Infinity War. In this list, we'll be recapping the ongoing storylines that could be mentioned in Infinity War, which is set for one of the biggest theatrical releases of all time. Whether you're still not sure what an Infinity Stone is or can already name every member of the Black Order, this list will get you up to speed on everything you should probably know before seeing Avengers: Infinity War.

25 CIVIL WAR

Captain America Civil War Poster

By 2016's Captain America: Civil War, the Avengers had been part of several city-destroying battles in the earlier Marvel movies. After another incident in Lagos, Nigeria left 26 civilians dead, the governments of the world passed the Sokovia Accords to regulate the MCU's superhero community. Iron Man led a faction of Avengers that supported the legislation, while Chris Evans' Captain America led a group of heroes who refused to sign the accords.

After Sebastian Stan's Winter Soldier, who's also Captain America's lifelong friend Bucky, was framed for a bombing, the two Avengers teams had a massive brawl at an empty airport terminal. At the end of that astounding action sequence, most of Captain America's team was defeated and taken into custody. Even though the whole conflict was engineered by Daniel Brühl's unmemorable villain, Baron Zemo, it still left Marvel's heroes fiercely divided.

24 THE SECRET AVENGERS

Captain America Civil War Team

As a result of the events of Captain America: Civil War, Captain America and his team went underground. After surrendering his shield to Iron Man, Steve Rogers broke all of his allies out of the Raft, a maximum security prison. After the breakout, the heroes split up, and Jeremy Renner's Hawkeye and Paul Rudd's Ant-Man seemingly retired from crime-fighting to spend time with their families.

In addition to growing an impressive beard, Cap has continued to work with Scarlett Johansson's Black Widow and Anthony Mackie's Falcon. As revealed in the comic book Avengers Infinity War Prelude, by Will Corona Pilgrim, Tigh Walker and Jorge Fornes, this secret Avengers team has been fighting villains around the world while staying out of sight. Despite their disagreements, Cap also left Iron Man with a phone where he and his team could be reached in case of an emergency.

23 THANOS

Thanos Josh Brolin Avengers Infinity War

Through brief appearances in The Avengers, Guardians of the Galaxy and Avengers: Age of Ultron, Thanos has been built up to be the most terrifying force in the MCU. Now, Josh Brolin's Thanos will be the main villain in Avengers: Infinity War, where his continuing efforts to amass power will take center stage.

Even though he's only had a collective two minutes of screen time so far, Thanos' presence has already been felt throughout the universe. In 2012's The Avengers, the Mad Titan sent Tom Hiddleston's Loki to invade Earth with an army of Chitauri alien warriors. In 2014's Guardians of the Galaxy, Thanos was revealed to be the father of Zoe Saldana's Gamora and Karen Gillan's Nebula, and he was betrayed by Lee Pace's unremarkable villain, Ronan the Accuser. Disgusted with the failures of his generals, Thanos decided to take matters into his own hands in Avengers: Age of Ultron's post-credits scene.

22 THE INFINITY STONES

Thanos (Josh Brolin) holds up the Infinity Gauntlet in Avengers: Infinity War

The Infinity Stones are the most powerful objects in the Marvel Universe. While each of them has a different set of abilities, the Infinity Stones were all created by an ancient group of cosmic beings around the beginning of time. When all six Stones are combined, the Space Stone, Mind Stone, Time Stone, Reality Stone, Power Stone and Soul Stone can give their wielder unlimited power. While they're far too powerful for most beings to touch, they can be used by some alien races or placed in a container that prevents direct contact with living beings.

Although they haven't all been called Infinity Stones, almost all of these objects have already appeared in at least one Marvel movie. In Avengers: Infinity War, Thanos will try to collect all of the Infinity Stones and place them in the Infinity Gauntlet, which would give him total control over the universe.

21 THE TESSERACT

Red Skull about to be teleported by the Tesseract

The first Infinity Stone, the Tesseract, debuted in 2011's Thor before playing a major role in Captain America: The First Avenger and The Avengers. The Tesseract, also known as the Cosmic Cube, is a crystal box that holds the Space Stone. During World War II, Hugo Weaving's Red Skull found the Tesseract and tried to use it to power Hydra's super-weapons. After he touched the Tesseract, the Red Skull disintegrated in an energy beam, and it fell into the Atlantic Ocean.

Later, Iron Man's dad, Howard Stark, found the Tesseract, and it ended up with S.H.I.E.L.D. In The Avengers, Loki stole it and used it to create a wormhole that allowed the Chitauri aliens to invade Earth. After he was defeated, Chris Hemsworth's Thor took the Tesseract back to Asgard for safekeeping. But as Asgard was being destroyed in 2017's Thor: Ragnarok, Loki quietly stole it, again.

20 LOKI WORKED FOR THANOS

Loki Tesseract Cube Infinity Stone

Over the course of three Thor movies and The Avengers, Tom Hiddleston's Loki has cemented himself as the MCU's biggest wild card. Although he was raised as Thor's adoptive brother, the Asgardian God of Mischief has tried to take over Earth and Asgard, where he eventually managed to impersonate King Odin for years.

After falling into a black hole in 2011's Thor, Loki made a deal with Thanos. In exchange for control over Earth, Loki would capture the Tesseract for the Mad Titan. Despite having the Chitauri army and another Infinity Stone, Loki failed. Even though he was able to save the Tesseract from being destroyed in Thor: Ragnarok, he didn't look too happy when he saw Thanos' ship in that movie's post-credits sequence. While Loki seemingly made peace with his brother, another encounter with Thanos could make him change sides again in Avengers: Infinity War.

19 VISION'S MIND STONE

Vision Mind Stone

In 2012's The Avengers, the Mind Stone was held in the Scepter that Thanos gave Loki. During that movie, Loki mainly used the Infinity Stone to turn S.H.I.E.L.D. agents into his mind-controlled lackeys. By 2015's Avengers: Age of Ultron, Tony Stark got his hands on the Mind Stone and used it to finish building Ultron, a sentient robot who promptly attacked his creators.

Ultron built a new "perfect" body with the Mind Stone implanted in its forehead. After Stark recovered the body, he uploaded his trusty robo-assistant J.A.R.V.I.S. into the empty shell. With a bolt of Thor's lightning, J.A.R.V.I.S. evolved into Paul Bettany's Vision. After proving himself worthy enough to pick up Thor's hammer, Vision quickly gained the team's trust and helped them defeat Ultron. With the combined abilities of the Mind Stone and his synthetic body, he still stands as one of Earth's most powerful heroes.

18 VISION AND SCARLET WITCH

Scarlet Witch and Vision in the kitchen in Captain America: Civil War

In both of her cinematic appearances, Elizabeth Olsen's Scarlet Witch has been at least partially responsible for some major destruction. After Ultron manipulated her into helping him in Avengers: Age of Ultron, she inadvertently directed a bomb blast into a building full of civilians in Captain America: Civil War. While those events made her something of an outcast, she found a sympathetic, synthetic friend in Vision.

As residents of the New Avengers Facility in upstate New York, the two Avengers bonded over their vaguely-defined powers, which both stem from the Mind Stone. Even though they were on different sides of Civil War, Vision rushed to her side when she was injured in the conflict. And as the comic book Infinity War Prelude revealed, she and Vision have been hiding out in Europe since Captain America broke her out of prison.

17 DOCTOR STRANGE'S TIME STONE

Doctor Strange Time Stone Eye of Agamotto 2

While the Eye of Agamotto might be one of Marvel's most powerful mystical artifacts in comics, it's only a carrying case for an Infinity Stone in the MCU. As revealed in 2016's Doctor Strange, the Eye of Agamotto holds the Time Stone. Over the course of the movie, Benedict Cumberbatch's Doctor Strange made liberal use of the stone, which can manipulate time on a massive scale.

Using the Time Stone, Doctor Strange was even able to trap Dormammu, the ultra-powerful ruler of the Dark Dimension, in a time loop until he was annoyed into submission. After this battle, Strange placed the Eye back in the protected walls of his training grounds, Kamar-Taj. Despite a warning about keeping the Infinity Stone out of sight, Strange casually wore the Eye of Agamotto in Thor: Ragnarok, and he'll wear it in Avengers: Infinity War too.

16 SPIDER-MAN'S OFFER

Spider-Man Iron Spider Armor

Since making his spectacular debut on Iron Man's team in Captain America: Civil War, Tom Holland's Spider-Man has had a pretty decent career in the MCU. In 2017's Spider-Man: Homecoming, he lost and regained Tony Stark's trust after an encounter with Michael Keaton's imposing Vulture. Unlike most versions of Spider-Man, Stark built Spider-Man's suit, which has a personal assistant and lots of hi-tech gizmos.

At the end of the MCU's first Spider-Man movie, Stark offered Peter Parker the Iron Spider suit, an even more advanced costume, and a spot on the Avengers. Even though he rejected that offer, Peter kept using Stark's first Spider-Man costume. While it may not matter in Avengers: Infinity War, Peter will probably have to deal with the fact that Marisa Tomei's Aunt May walked in on him in his Spider-Man costume at some point soon too.

15 THE COLLECTOR'S REALITY STONE

The Collector with the Aether aka Reality Stone in the end credits scene for Thor 2

While 2013's Thor: The Dark World might not be the most celebrated Marvel movie, it was centered almost entirely around the Aether, another Infinity Stone. While the most of the Infinity Stones are solid objects, the Aether is a liquid version of the Reality Stone. As Thor learned in that movie, the Reality Stone can warp the laws of physics and convert matter into dark matter.

After Christopher Eccleston's Malekith unsuccessfully tried to plunge the universe into eternal darkness with the Aether, the Asgardians took the Reality Stone. Since they didn’t want to keep two Infinity Stones in the same place, the Asgardians gave the Aether to Benicio del Toro's Collector for safekeeping. While it hasn't been seen since then, del Toro's eccentric cosmic character should still have the Infinity Stone in his collection.

14 NO MORE MJOLNIR

Hela catches Mjolnir in mid-air, in Thor: Ragnarok

With the possible exception of Captain America's shield, Thor's hammer, Mjolnir, is the most famous weapon in the MCU. Forged by the Dwarves of Nidavellir in the heart of a dying star, the hammer could channel the God of Thunder's lightning powers. Famously, the hammer could only be wielded by those deemed "worthy" enough to wield its considerable powers.

Even though it's one of the few objects that could legitimately challenge the Infinity Stones, Mjolnir was completely destroyed in Thor: Ragnarok. After Anthony Hopkins' Odin died in that 2017 movie, Cate Blanchett's Hela, who was also Thor's long-lost older sister, confronted Thor and his adoptive brother Loki. When Thor hurled his hammer at her, she grabbed and crushed it with her enchanted Asgardian strength. Even though he defeated her, Thor will be missing his signature weapon when Avengers: Infinity War begins.

13 THE POWER STONE

Orb Power Stone Star Lord Nova Corps

In 2014's Guardians of the Galaxy, Chris Pratt's Star-Lord proved himself to be one of the few Marvel characters who could openly wield an Infinity Stone. Near the start of the movie, Star-Lord stole the Orb, a metal case that held the Power Stone. Except for the half-Celestial Star-Lord, the Power Stone obliterated anyone who touched it without protection with an explosion of purple energy.

In the final moments of that movie, the Guardians gave the Orb to the Nova Corps, an intergalactic peacekeeping force. Led by Glenn Close's Nova Prime, the organization is based on the alien planet Xandar, where hundreds of Novas died trying to rescue the Orb from Ronan the Accuser. Since then, the Power Stone has remained locked away under armed guard in the Corps' vault.

12 GUARDING THE GALAXY

The Guardians of The Galaxy gathering in Avengers Infinity War

While they might not get top billing in Avengers: Infinity War, the movie will also mark the next on-screen appearance for the Guardians of the Galaxy. For the most part, the team hasn't really changed too much since it burst onto the screen in 2014. After Groot sacrificed his life their first movie, his young seedling joined the team in 2017's Guardians of the Galaxy Vol. 2. As one of that movie's post-credits revealed, the new Groot has already grown into a moody teenager.

After Star-Lord learned about his half-alien heritage in the 2017 sequel, Pom Klementieff's Mantis also joined the team. Using her emotion-manipulating powers, she was tasked with soothing Kurt Russell's Ego, a would-be alien conqueror and Star-Lord's father. After he went mad, she betrayed her master and helped the Guardians save the galaxy.

11 THANOS' FAMILY MATTERS

Gamora Nebula Infinity War

Both Guardians of the Galaxy movies have also highlighted the relationship between two of Thanos' daughters, Zoe Saldana's Gamora and Karen Gillan's Nebula. Both aliens were adopted by Thanos and raised to become some of the most dangerous assassins in the universe. When he made the pair fight as children, Thanos gave Nebula painful cybernetic "upgrades" whenever she lost a sparring match.

While Gamora had already turned against Thanos before Guardians of the Galaxy, Nebula betrayed her father and joined Ronan the Accuser during that movie. In Guardians of the Galaxy Vol. 2, Gamora and Nebula formed an uneasy friendship as they began to bond over the shared trauma they suffered under Thanos. Although Nebula worked with the Guardians, she took off to hunt Thanos down on her own at the end of the movie.

10 IRON MAN'S BATTLE SCARS

Tony Stark Avengers Infinity War

Even though Marvel's galaxy has played an increasingly big role in the MCU, Iron Man is the only one of Earth's heroes who has his eyes on the skies. After briefly traveling into deep space in 2012's The Avengers, Iron Man had anxiety attacks and built an Iron Legion of automated armors to protect the Earth in 2013's Iron Man 3.

Although he briefly retired from being Iron Man, Stark was left to pick up the pieces of the Avengers after the conflict in Captain America: Civil War. Things got a little bit better for Tony when he rekindled his relationship with Gwyneth Paltrow's Pepper Potts. Without a full Avengers team to rely on, Stark refocused his efforts on creating the ultimate suit of Iron Man armor for himself. As Avengers: Infinity War Prelude revealed, Stark wants to be able to handle any intergalactic threat on his own.

9 HULK'S RETURN

Hulk Thor Ragnarok

In 2017's Thor: Ragnarok, Mark Ruffalo's Hulk dazzled audiences with his turn as a super-strong alien gladiator in the Contest of Champions. Once Thor rescued his "friend from work," the Hulk transformed back into the neurotic scientist Bruce Banner for the first time in two years. Although he was understandably hesitant about changing back into the Hulk, he ultimately transformed back into the Green Goliath to help Thor defeat Hela.

Along with Thor and his allies, Hulk will start Avengers: Infinity War on a spaceship that’s traveling towards Earth. This will mark the first time Banner has been back on his homeworld since 2015's Avengers: Age of Ultron, when the Hulk flew an Avengers aircraft into deep space. During the Hulk's self-imposed exile, Banner missed a lot of time, so he could still be worried about transforming back into the Hulk.

8 BLACK WIDOW'S RUN

Captain America and Black Widow standing together

Even though Scarlett Johansson's Black Widow was on Iron Man's team in Captain America: Civil War, she turned on the team at a pivotal moment. After letting Captain America escape, both Iron Man and Chadwick Boseman's Black Panther felt personally betrayed. With a terse warning from Tony Stark, Black Widow went into hiding, since the government wanted to arrest her for helping the other fugitive Avengers.

Even though she was stood against them on the Sokovia Accords, Black Widow joined up with Captain America and Falcon. As revealed in the Avengers: Infinity War Prelude comic, she used a new blonde hairstyle and a lifetime of counter-intelligence training to disguise herself and stay ahead of the law. Using her old espionage contacts, she and the covert Avengers quietly tracked down an alien weapons shipment and neutralized it.

7 HAWKEYE'S FAMILY

Hawkeye and his wife in Avengers Age of Ultron

While he might be the best archer in the Marvel Universe, Hawkeye hasn't always played the most glamorous role in the Avengers. After Jeremy Renner's character was mind-controlled for most of 2012's The Avengers, he made a surprising revelation in 2015's Avengers: Age of Ultron. When the Avengers were looking for a place to recover, Hawkeye took them to his secret homestead, where his previously unmentioned family lived.

In this completely off-the-books location, Hawkeye and his wife Laura, played by Linda Cardellini, live with their three small children. At the end of Age of Ultron, Hawkeye retired from action to spend more time with his family. After Captain America called him back into action for Captain America: Civil War, he was arrested along with the rest of Cap's team. As soon as Cap broke him out of the Raft, Hawkeye resumed his retirement and returned to his family.

6 SHATTERED S.H.I.E.L.D.

SHIELD agent Maria Hill played by Colbie Smulders in the MCU

Led by Samuel L. Jackson's Nick Fury, the international espionage organization S.H.I.E.L.D. was instrumental in bringing the Avengers together for the first time. After the organization was infiltrated by hundreds of double agents in 2014's Captain America: The Winter Soldier, S.H.I.E.L.D. was basically disbanded. While the agency has been rebuilt on a much smaller scale on the TV show Agents of S.H.I.E.L.D., Fury and some other ex-S.H.I.E.L.D. agents used some spare equipment to save civilians in Avengers: Age of Ultron.

While Fury isn't set to make another appearance until 2019's Captain Marvel, Maria Hill, his former second-in-command, will show up in Avengers: Infinity War. Portrayed by Cobie Smulders, Hill has appeared in several MCU movies and in a few episodes of Agents of S.H.I.E.L.D. In her most recent appearance, Hill was seen in the New Avengers Facility, along with the rest of the team's support staff.