Ryan Reynolds plays Guy, a man who exists only in a video game. He is what is known as an "NPC", or non-player character, the game equivalent of a movie extra: someone who serves only to populate the background.
One day, Guy bumps into an attractive "hero" character named Molotovgirl (Jodie Comer) and, to his surprise, becomes self-aware. No longer content to deliver the same lines over and over again in his job as a bank clerk who is robbed daily (the game is sort of modeled on the Grand Theft Auto series, in which players can get up to all sorts of mayhem in a realistic city scenario), Guy finds himself falling for Molotovgirl, and will do whatever it takes to win her heart. That means, effectively, breaking out of his "non-player" routine and fighting the actual players, much to their surprise.
In the real world, Molotovgirl is an avatar controlled by Millie (Comer again), an unemployed computer programmer whose artificial intelligence software was coopted into the violent video game that Guy lives in. Her code stolen by a hilariously awful tech CEO named Antwan (the ubiquitous Taika Waititi), Millie tries to get her old partner Keys (Joe Keery, the innately likable breakout star of Stranger Things) to help her dig deep into the game to find the proof that would expose Antwan's theft. Slowly they realize that Guy is a byproduct of their own AI efforts, and so they enlist him in their cause.
Free Guy is great fun, and it's nice to see an effects-laden Hollywood blockbuster be borne from an original screenplay (story by Matt Lieberman, screenplay by Lieberman and Zak Penn), although I should put "original" in quotes as the story borrows liberally from pop culture touchstones like The Matrix, Tron, The Truman Show, They Live, Groundhog Day, and I'm sure many others. And I wish it could have explored its existential premise a little more – it wouldn't have necessarily lost any energy in the process, and with a little more depth, the resultant film could have been a classic. As it stands, Free Guy is just good old fashioned Hollywood fare, the perfect popcorn movie.