Avengers: Infinity War is the first of the epic two-movie crescendo to tie up the initial run of MCU films. The movie was directed by Joe and Anthony Russo and brings back the entire slate of MCU characters and actors, including Robert Downey Jr., Scarlett Johannson, Chris Hemsworth, Chris Evans, Mark Ruffalo, Tom Holland, Elizabeth Olsen, Paul Bettany, Benedict Cumberbatch, Anthony Mackie, Tom Hiddleston, Don Cheadle, Chris Pratt, Sebastian Stan, Zoe Saldana, Vin Diesel, Chadwick Boseman, Jeremy Renner, Bradley Cooper, and Karen Gilian. It also, finally, sees the arrival of Josh Brolin's Thanos after multiple teases in various movies or end-credit sequences.
This, as most are aware, is the movie that the entire MCU slate of movies has been building up to. As I said above, Thanos finally arrives, making good on his threat in the post-credits scene in Age of Ultron to do things himself. It starts where the end-credits scene in Thor: Ragnarok left off, with Thanos attacking the Asgardian ship. The movie then finds a way to weave in most, but not all, of the characters from the other movies in an attempt to keep the various infinity stones away from Thanos. The "main" Avengers lineup get the most screen time, while the amount of time the other characters are in the movie varies. I won't spoil anything for those who may not know how it turns out, but it has massive repercussions for the MCU storylines going forward.
The 4k set is a two-disc set. The UHD disc has just the movie itself, which looks and sounds great, as you would expect. The extras are on a regular blu-ray, with about 30 minutes of behind-the-scenes and making-of featurettes, a gag reel, deleted scenes, and a commentary track on the movie. It is definitely one of the best movies in the group 19 or so movies in the MCU that had been released up to that point. Even if you have a bit of superhero movie burnout, it is worth checking out to see all the stories finally tied together.