From “The Last of Us” to athlete’s foot commercials, fungus does not have the best of reputations on television. But what if it could save us all?

“Common Side Effects,” a wryly funny animated conspiracy thriller beginning Sunday on Adult Swim, suggests that not everybody would be pleased.

Marshall Cuso (Dave King), an eccentric environmentalist and self-employed scientist, discovers a rare mushroom on an expedition to Peru. The fungus, a ghostly specimen called the Blue Angel, can cure almost any illness and heal seemingly fatal injuries — including the ones Marshall sustains when he is attacked by gunmen immediately after making his discovery.

Back in the States, pursued by the Drug Enforcement Administration and other, more mysterious figures, Marshall runs into Frances Applewhite (Emily Pendergast), his former school lab partner who is now unhappily working for a pharmaceutical giant. Together, they make a pact to bring the magic mushroom to the people and protect it from the forces who would like to erase all traces of its existence.

Who are those forces? Them. And who’s them? “Big Pharma, the insurance companies, the government,” Marshall explains. “All the people who make tons of money just from keeping us sick.”

A figure like Marshall — nerdy, neckbearded, with a prominent belly hanging from his Hawaiian shirt and one big theory that explains it all — would usually be portrayed on TV as, at best, a well-meaning kook, a side character who exists for laughs and exposition. Even in the conspiracy-riddled world of “The X-Files,” he would be more of a Lone Gunman than a Fox Mulder.

Place him in the context of 2025 current events — populist pushback against the medical industry, the politicization of “wellness” language and the strange bedfellows of Make America Healthy Again — and things get even more interesting. Marshall has literally done his own research and discovered that nature holds wonders that “they” are hiding from you.

That “Common Side Effects” takes him seriously as a hero — albeit in the spirit of quirky action-comedy — suggests that we are dealing with an unusual specimen here.

The series is created by Steve Hely, whose comedy credits include “Veep” and “The Office,” and Joseph Bennett, whose spectacular 2023 animated series, “Scavengers Reign,” shares philosophical and aesthetic DNA with this project. “Reign” took place on an alien planet filled with hostile and beneficent flora, rendered in acid-trip imagery. “Common Side Effects” brings this psychedelic awe for the mutability of life Earthside.

The producers include Greg Daniels and Mike Judge, who collaborated on “King of the Hill.” Judge — who also voices the tetchy, put-upon chief executive Frances works for — might seem a particularly odd match for this story at first glance. His comedies, like “Beavis and Butt-Head,” “The Goode Family” and “In the Know,” often delight in punching hippies of Marshall’s stripe.

But look deeper in his work and you will see that Judge thrives in the space between the ends of the cultural horseshoe, where conservative and progressive anti-establishmentarianism converge. “Idiocracy” was a Bush-era spoof of a dumbed-down America that killed plants by feeding them sports beverages; “Silicon Valley” involved the push to build a decentralized internet that threatened big tech companies.

If anyone can find the Venn diagram of Luigi Mangione’s and Robert F. Kennedy Jr.’s Americas, it might be this team.

As a conspiracy thriller, “Common Side Effects” is decidedly an ordinary button mushroom. In the four episodes screened for critics, the action twists are familiar and the members of its shadowy cabal underdeveloped.

What makes the series captivating is its style and deadpan voice. The two D.E.A. agents put on Marshall’s case, Copano (Joseph Lee Anderson) and Harrington (Martha Kelly), are an oddball well-meaning pair who might have walked out of a ’90s indie comedy.

The narrative pace is laid-back and appealingly digressive. And the art shares with “Scavengers Reign” a realism blended with a flair for the baroque and mystical, particularly when it renders the workings of the Blue Angel fungus, which connects the creatures it heals with the universe on a cellular level.

But maybe most refreshing is how “Common Side Effects” manages to tell a pointed, conspiracist story without cynicism or despair. As it goes on, it seems as if the series’s true heart may be not Marshall but Frances, an Everywoman who has been pushed by circumstance to make compromises but who wants to be better and to do better.

This, in the end, seems to be this magical and whimsical series’s diagnosis. It sees a system full of obstacles but with only a few true villains. It does not see humanity as a disease eating away at the Earth but as an ecosystem component that needs to be nudged into better alignment with the whole. It sees a society that is often sick or misguided but is not irredeemable. There just happens to be shroom for improvement.