First, I’d suggest watching a couple of the movies leading up to Infinity War, though I’d alter the list slightly. It’s much shorter, for a start:

Captain America: The First Avenger (2011)

This one’s the first in the MCU to introduce what we came to know was an Infinity Stone, which are the big, reality-warping MacGuffins that are fueling this whole saga’s overarching story. The Tesseract is used to power weapons here, but it’s also an item that can warp space, as well. (First Avenger is also one of my favorite MCU movies overall and deserves more love).

The Avengers (2012)

Yeah, I’m skipping the first two Iron Man movies here. You shouldn’t, if you haven’t seen them. But they’re not as necessary to understand what’s going on with Infinity Stones, and Avengers is. Y’see, Avengers features two of the total six Infinity Stones. The Tesseract returns here and Loki, brother of Thor, carries another one around in a nifty little staff/cane weapon he uses to brainwash enemies to his side. This Marvel film is also the establishment of the Avengers team for the first time, and that’s important.

Thor: The Dark World (2013)

This one kinda lags a bit, I’ll be honest. But there’s an Infinity Stone (The Reality Stone, guess what it does) involved and you kind of need to see it to get where they all are by the start of Infinity War, as the going theory as of this writing is that Thanos, Big Universal Bad, will be on a rampage to acquire them for his Gauntlet. Also, Kat Dennings is a treasure and she’s great here.

Guardians of the Galaxy (2014)

Another favorite of mine, this one introduces a new, secondary team focused on cosmic threats out in space. We also see the closest that Thanos gets to an Infinity Stone for himself, with his lackey Ronan taking the Power Stone for himself. He then loses it in a dance-off, but it’s the getting it at all that matters.

Avengers: Age of Ultron (2015)

Here, the assembled Avengers face a new threat, an AI unleashed from the Infinity Stone within Loki’s recovered staff, who takes on the name Tony Stark gave to his global defense project: Ultron. The Mind Stone eventually comes to reside in the forehead of the sentient android Vision, who is awakened by the combined power of the Avengers themselves to stop the threat posed by Ultron.

Captain America: Civil War (2016)

In this film, often referred to as, "Avengers 2.5" because the focus is so clearly on the team and not Cap himself, there are no Infinity Stones here. But the team fractures due to internal conflict, which will likely play an important role in how they approach the existential threat in Infinity War, so understanding where everyone’s left before Infinity War starts just seems important. It’s also a damn fun movie that (re?)introduces Spider-Man to the Marvel films.

Doctor Strange (2016)

Actual, factual, honest-to-Cyttorak magic gets introduced to the Marvel film universe in this film, positioning broken surgeon Stephen Strange as the last remaining bulwark against threats mystical and supernatural. He also does some fun stuff with the Eye of Agamotto, which in the Marvel films stands in for the Time Stone among the Infinity Stones.

This lineup leaves a few Infinity Stones out in the wind, you’ll notice—that’s because the film series has, too, and Infinity War will feature lots of fighting over the ones still in the wild. This list provides a solid idea of who’s who in the MCU, and where the big-ticket items left fighting over are, at the start of the new release.