This is what summer movies are all about — “The Tomorrow War” is about endearing but flawed humans fighting aliens as they save all of humanity and resolve their family estrangements. Plus time travel. I’ll have a couple of concerns later on, but let’s do what the movie does and get right to the action.

Plunged right into the action is more like it, as the movie opens with humans firing at terrifying, insect-lizard-like aliens we will later learn are called White Spikes as they fall from the sky into the ocean.

That’s just a peek. As the hero we’ve just seen (Chris Pratt as Dan) plunges into the water, we are plunged back in time, as far away from the action as we can imagine. It is 28 years earlier in a quiet suburb. Dan is coming home, where his wife (Betty Gilpin as Emmy) and daughter Muri (Ryan Kiera Armstrong) are hosting a Christmas party. Dan is distracted because he has applied for a new job, one he would find more satisfying than the high school teaching position he took after leading missions with the military in Iraq. He settles down to watch a football game with Muri, but there is static on the screen and then an unbelievable sight. People disembark from what look like spaceships. They say they are from 30 years in the future, where humans are fighting a war with alien invaders and losing badly. Their only hope is to bring people from the past to help them fight.

A year later, systems have been set up to conscript people to join the fight. Only half of people are “qualified” for time travel, and they are sent for one-week tours of duty. Only 25 percent of those who are sent through time survive, and those that do are severely injured and traumatized. People are losing support for the war and for the world governments that are running things. “Why should we be fighting a way that as far as we’re concerned hasn’t happened yet?” But there is no choice. If you try to avoid service, your spouse or child is sent in your place.

Nevertheless, Emmy urges Dan to run. His only hope is to get help from the father he swore he would never speak to again (J.K. Simmmons as James). He meets with James but decides he would rather fight the aliens.

The actions scenes are exciting and the script by Zach Dean keeps things moving, even with the nearly 2 1/2 hour running time, nicely balancing character, combat, and some humor. As we’ve seen in “Guardians of the Galaxy” and the “Jurassic World” movies, Pratt is a classic American hero, part cowboy, part smart aleck, loving father and husband despite some struggles to be the man he wants to be to them. There are some clever twists — also some not so clever twists, but time travel stories seldom avoid paradoxes. The disappointment here is a brief but jarring jab at the government, which makes no sense given the essential role the government plays in a crucial development, especially unwelcome in a 4th of July release. When compared to the ultimate in this category, “Independence Day,” where the President literally gets in a plane (after a stirring St. Crispin’s Day-style speech) to fight the aliens, it is impossible not think about what prompted it. Even in a summer action movie.

Parents should know that this is a PG-13 sci-fi action film, which means a lot of “action-style” violence. There’s lots of alien blood and body parts but though we hear a lot about human fatalities we do not see much beyond a lot of dead bodies and some skeletons. Characters use some strong language and drink some alcohol and there are mild sexual references.

If you like this, try: “Independence Day,” “Source Code,” “Pacific Rim,” and “Battle: Los Angeles”