When the apocalypse comes, we’re all going to want chimps, gorillas and orangutans on our side. With “Dawn of the Planet of the Apes,” they’ve already come to Hollywood’s aid. In a lackluster summer for movies, this surefire hit should have its producers swinging from the girders.

“Dawn” is that rare sequel that makes a pretty good predecessor (“Rise of the Planet of the Apes”) seem almost unnecessary. Building on the setup — a chimpanzee named Caesar acquires human language skills from a loving scientist and leads a band of escaped lab apes to a new, free life in the redwood forest outside San Francisco — it delivers not only more than twice the action, but the kind of smart, emotionally rewarding story almost never found in standard-issue blockbusters.

A lethal virus, dubbed “simian flu” because it originated in the same lab that experimented on Caesar (Andy Serkis) and his cohorts, has decimated the human population, leaving only a ragtag band of genetically immune survivors tenuously led by Gary Oldman.

Meanwhile, deep in the woods, Caesar has built an army of loyal followers — on horseback! — and a family of his own. The little treetop nation lives by the credo “ape not kill ape” (don’t call them monkeys, please; monkeys have tails, which apes do not, and less-evolved brains). But when some humans cross into ape territory intent on reaching a dam that can restore electrical power to the city, bad apples on both sides threaten to set off a massacre as their well-meaning counterparts forge interspecies bonds.

Although Jason Clarke turns in a strong performance as top good-guy Malcolm, “Dawn” features zero A-list stars. By design, the humans are strictly B-list compared with the incredibly lifelike, CGI-rendered apes — Caesar, his loyalty-torn son, and his violent ally Koba, whose bloodlust could topple both worlds. We should perhaps be alarmed that the nuanced facial expressions artificially generated on the apes tug at the heartstrings more effectively than those of the human actors.

A quibble: Would it have killed director Matt Reeves to toss in one female character who does more than breed or reassure and bandage the menfolk? The double whammy of patriarchy in both human and ape camps is needlessly heavy-handed.

Sociopolitical analogies beyond the obvious war tropes abound. As the apes swing through the giant trees, increasingly agitated by the threat of encroachers with superior resources, “Occupy Redwood” springs to mind. The gun-control set will claim a resemblance between the slack-jaws hiding behind their semiautomatics and the photos of those open-carry dudes at Target. When the apes get their hairy mitts on the humans’ weapons stash, gun enthusiasts will applaud the upset in the balance of power.

In the end, the lesson learned for each side is that “They want what we want — to survive.”

The lead characters in most blockbusters exhibit emotions with impatience at best, cartoonish bathos at worst. Let’s hope “Dawn of the Planet of the Apes” is also the dawn of a new type of big movie — as packed with feeling and intelligence as it is with action and special effects. At the very least, it should spur a burst of upper-arm exercises on playground monkey bars everywhere.