Rest assured, this is a spoiler-free review of Avengers: Infinity War. Should you choose to comment on our Facebook post after seeing the film — or if you’ve been unable to contain yourself from excavating spoilers on your own — please respect the spirit in which this review was written and refrain from mentioning key revelations.

What does it mean to be Earth’s mightiest heroes? Yes, it means possessing the force to fling puny gods. Or the ingenuity to engineer (now mostly automated) armor that saves the ones you love (if never truly yourself). Or the integrity of breathing your ethics … and pivoting to redefine them whenever they’re perverted or exploited.

For the last 10 years, we’ve thrilled, chuckled and, at times, deeply ruminated on Marvel Studios’ unprecedented 18-film tapestry of tones and talents — unrivaled by any contemporary franchise and unlikely to ever be equaled. But as far as crossover events go, no matter how enjoyable: If we’re being honest, who or what have the Avengers really had to avenge (outside of a S.H.I.E.L.D. agent revived in prime-time or a one-and-done speedster)?

When you avenge, you strike back in honor of something or someone often swiftly and unexpectedly taken away. Vengeance is a furious attempt to resolve an equation of tough, irretrievable loss. It also rarely computes. Screams of retaliation have nothing on that deafening roar in the absence of what’s gone.

That absence is an immediately imposing presence in Avengers: Infinity War. Gone is the rousing fanfare over the Marvel Studios credit card, replaced by the low rumble of ominous strings. (The only victory lap is watching the “io” in “Studios” morph into a “10.”) And if you presume this is just a way of saying “people die,” remember: The best Marvel films condition us to recognize that our heroes’ comforting ideologies suffer their own mortal wounds.

Infinity War earns its place among that top tier — bold in ways as inspiring as they are often unmooring. It only sounds hyperbolic to say that, ultimately, it is unlike any Marvel film to come before. Certainly more than either previous Avengers film, it examines the difficulty of bridging the gap between heroism and human nature.

For reasons that are sundry, unassailable and often yours and mine alone, these women and men are heroes to all of us — as children and adults, if we’re marginalized and melancholy, no matter our walks of life. To each other, they are Tony, Steve, Nat, Bruce, Wanda and, as some of Infinity War’s newer nicknames go, “Viz,” “Rabbit” and “Pirate Angel.” They are congenial, but also confused, conflicted and fragile. Sometimes, collapsing into a friend’s arms is the only solace they can find. Sometimes, the misunderstandings, regrets, mistakes and monumental confrontations rear their heads. Inheriting the flagship story after two excellent Captain America films, directors Joe and Anthony Russo capitalize on the push-and-pull of that simultaneous nearness and distance.

The plot is simple: Thanos is here. He’s no longer a credit-cookie abstraction, a subplot invocation, a long-game play. We know he’s the one who solicited Loki’s invasion of Earth. We know he orchestrated Ronan the Accuser’s attempt to wipe out the galaxy. Here, Thanos pulls back the curtain in an opening gambit that establishes two things: He doesn’t mess around, and he’ll make every one of our heroes eager for a turn at his thick, purple throat.

Mathematics factor into his plan, too, albeit with a “dispassionate” randomness absent from the equation of vengeance. Thanos’s home world, Titan, accelerated into disrepair and decay. His proposal? Kill half the population by a random draw. No favorites, no breaks, no other way to save Titan. After he was laughed off as a madman, Titan fell to ruins and Thanos embarked on a quest to “help” other planets evade the same fate. Josh Brolin infuses Thanos with both seemingly indomitable menace and a sense of weary, insistent duty — a hypocritical messiah insisting there’s a certain sense of love within his method and assembling acolytes from the wreckage he’s left behind. For a guy strong enough to lasso moons, the reliance on zealous violence to prove himself right introduces unexpectedly disturbing parallels with the real world.

As you may remember, Gamora — she of Guardians of the Galaxy — is one of Thanos’s adopted daughters. On her planet, Thanos’s plan worked, and since the 2012 Battle of New York, he’s been systematically moving his way toward Earth. If he acquires all six Infinity Stones — Space, Reality, Power, Mind, Time and Soul, as teased in previous films — and fuses them in a gauntlet, he can wipe half of Earth’s slate clean with a wave of his hand.

To attempt a bargain with Thanos is like bargaining with cancer (the futility of which one character knows all too well). So, working to stop him at various fronts on Earth and elsewhere are most of our known Avengers, as well as Doctor Strange, Black Panther, Spider-Man and the Guardians, splintered into inspired, sometimes surprising factions.

All too often, well-managed traffic is what passes for “quality” in stories stuffed with this many characters. Even at 150 minutes, co-writers Christopher Markus and Stephen McFeely certainly prioritize relationships and arcs. But they still find time for unexpectedly amusing, and emotionally truthful, revelations throughout; I remain amazed at the emotional investment I’ve found in one character who says “I could sure lose a lot” under his breath — out of earshot from anyone nearby, uttering it aloud if only to remind himself that, much to his surprise, he believes it.

It’s inevitable that a few characters peace out, but the Russos maintain crisp momentum and balance; we’re never thinking about who hasn’t popped up yet or how long it’s been since we checked in on someone. Neither is there unnecessary intercutting or the interruption of a moment we need to see in favor of superfluous spectacle.

If there’s any knock on the character work, it’s the generic undercard of Thanos’s lackeys in the Black Order. They’re obsequious brutes sent to wipe out those who foiled his previously outsourced plans while he pursues the Stones. Only one is mentioned by name. Another resembles an irritated Na’vi. Are they true believers or cowed survivors? Regardless, they leave little of the wonderstruck impression with which my well-versed comic-book friends tend to speak of them.

Infinity War fares far better with the array of new worlds and vessels to which it takes us. There is a moment aboard Thanos’s ship where cinematographer Trent Opaloch’s simultaneous framing of someone beside their own hologram carries the silently heartbreaking symbolism of a soul’s self-betrayal. On a more majestic level, there’s the intergalactic forge of Nidavellir, the barren expanses of the planet Vormir and Thanos’s own Titan, arguably the location of this mammoth movie’s most highly charged action moments. Tasked to exceed the earthy grit of his Captain America work, Opaloch conveys a sense of tactile, elemental weight in all corners of the galaxy — a story of frost and fire, land and space, with the action in all of them cleanly conveyed and precisely escalated.

For all of its stakes-never-higher weight, there’s still room for plenty of humor in Infinity War, from meta-jokes about product placement or popular culture to the inevitable clash of egos between Stephen Strange and Tony Stark and the MCU’s parade of pretty Chrises. (See for yourself if the Russos get all three in the same scene.) After all, friends laugh with each other. Here, it’s what they do because they’d sometimes otherwise cry.

Therein lies an unmistakable sense of culmination in a cinematic universe that has, to this point, emphasized continuation. Only now has the MCU arrived at a place where bluffs can be irrefutably called and gauntlets, real or metaphorical, can be thrown down. With unquestionable audacity and thoughtfulness, Infinity War upends the comparative breeziness of all that came before it.

But it also reinforces that, well beyond Vision’s contorted genetic composition, the best parts of these heroes are irreversibly intertwined in one another, bonds that exceed blood. Infinity War suggests that at least trying to inspire that togetherness in others — even half-Celestial, half-Missourian strangers you meet while trapped on alien spacecraft — is a kindness we’d do well to wield in the real world. It understands that the only thing through which we can sustain untenable loss is each other. If only our heroes can recognize that, well … that’s mighty.

What does it mean to be Earth’s mightiest heroes? It’s the ultimate question with which they’ve wrestled for 10 years. The answers await behind a stunning, challenging final hurtle of truth and consequences … and that is Infinity War.