It’s amazing how much a little good acting can lift an FX-extravaganza. Josh Brolin is a total riot playing a younger version of Tommy Lee Jones’ Agent K — he’s perfected the appraising squint, the tight jaw, the sardonic drawl. And it’s been so long since Will Smith has been on the big screen — four years, in fact — that I had forgotten how ridiculously likeable he is. The chemistry between Smith and Jones, and between Smith and Brolin, is just a joy. Emma Thompson, meanwhile, brings British wit to the proceedings as an agency boss, although her role feels truncated. And, yes, the otherworldly monsters are cool, and the time travel back to 1969 (so Smith can save Jones/Brolin from an alien murderer) is fun, although the story gets covered in cheese near the end. But “MIB3” serves its role as breezy summer-movie fun.

— Kristina Dorsey