EARLY in “Avengers: Infinity War”, one of the heroes stares almost directly into the camera and declares, “Look, it’s not overselling it to say that the fate of the universe is at stake.” Ostensibly he is cajoling another movie-star hero, Robert Downey junior’s Iron Man, to come with him. But the real audience for this moment of winking self-awareness is on the other side of the screen. It is a wry acknowledgment of the dramatic limitations of a genre that Disney dominates as utterly as the most fearsome comic-book villain. Naturally the fate of the universe is at stake. Equally, though, the fate of the Universe—the Marvel Cinematic Universe (MCU)—is not.

Superhero flicks are unavoidably formulaic. The heroes are difficult to kill not because of their superpowers, but because they serve a higher power, an industrial blockbuster economy. The superstars each get their screen time, in a loose correlation to their importance to fans. Their defeats are ephemeral, even when they die (or appear to). They are part of the ineluctable journey to a climactic battle, which in turn points the way towards more films.

Given these constraints, “Infinity War”, the 19th film in the MCU, is a remarkable achievement. It manages to weave together several action storylines, each carried by a subset of familiar heroes. Together, on Earth and other distant planets, they seek to thwart a villain’s Malthusian quest to wipe out half the population of the universe. Despite the grave nature of this mission, “Infinity War” is also one of the funniest MCU sagas. Some main characters perish, and most others are frequently at risk of doing so, but the heroes never stop making fun of each other, their adversaries and the carnage around them.

And it works. The filmmakers—Kevin Feige, the maestro of Marvel Studios, Anthony and Joe Russo, the directors, and Christopher Markus and Stephen McFeely, the writers—have worked out that it is much more enjoyable and sensible to call attention to the rules of their play-universe than to pretend that they do not exist. One-line quips and witty repartee would be dangerously distracting in actual mortal combat, but everyone knows most of the combat is not mortal, even by the absurd standards of action films. That is why one character muses aloud about whether the death of another is real “this time”. During another sequence Spider-Man asks, “Why does somebody always have to die in this scenario?” Even a hero’s last gasp is played for laughs.

These gags work because the audience is in on the joke. They know the rules of the MCU, and the stakes, before they walk into the cinema, suspending disbelief of their own accord. To pretend otherwise would be an insult, and set the film up to fail. A rival comic-book series, the DC Entertainment Universe, has taken itself more seriously, with much poorer results. “Justice League”, DC’s own superhero-ensemble movie, earned about as much at the North American box office ($229m) as “Infinity War” is projected to take in its first weekend alone.

By contrast, MCU’s embrace of the genre’s limitations helps stave off fatigue. That most MCU enthusiasts will be excited to see “Infinity War” is a coup in itself. It is less a work of art than of commerce, but it proves there is artistry in the post-modern trick of making a superhero film fly.