Donald Trump is out of office but QAnon holds sway. Last September, Trump posted an image of himself with a Q lapel pin and the words “The Storm is Coming”. A few months later, Liz Crokin, a QAnon promoter, spoke at Mar-a-Lago and posed with the former president. In one photo, the pair flashed a “thumbs up” sign.

QAnon is the latest great American conspiracy theory. Its key beliefs: a secret cabal “controls global governments”, the 2020 election was stolen, Hollywood and liberal elites crave the blood of children in bid to sustain their youth. You read that right. QAnon is rife with stories of “mole children”, stashed away in caves for the delectation of the rich and powerful.

“The suspicious 2019 jailhouse death of wealthy pedophile Jeffrey Epstein … prompted new public interest in the idea of powerful elites abusing children,” Will Sommer writes.

With his first book, the Daily Beast reporter jumps into this steaming cauldron of conspiracy and distrust. He emerges to offer a close examination of the rise and continued presence of QAnon on the American political landscape.

Detailed and impeccably researched, Trust the Plan is essentially a crash course on a volatile and vocal segment of the US population. It is unlikely Sommer will win hearts and minds. Trust the Plan is essentially written for blue (Democratic) America. But it is eye-opening, nonetheless.

Sommer has spent considerable time among QAnon adherents. At a May 2021 conference in Texas, they treated him suspiciously and accused him of trespassing. “You should be ashamed of yourself!” an elderly woman scolded. The walk of shame stuck with him. Sommer takes QAnon seriously – as do Republicans, as should Democrats.

QAnon followers are largely young, male and lack a college degree. They are disaffected but not oblivious. For them, the Great Recession left its mark. Marriage and stability became luxury goods. Life expectancy and birth rates receded. Covid turned the world on its head.

QAnon is sufficiently amorphous to adapt to changing facts and realities. It can muster the devotion and fanaticism of a religious group. The dream never dies.

QAnon logos and banners loomed large on January 6, in the prelude to and the aftermath of insurrection. QAnon adherents did not know what to make of Mike Pence, Trump’s vice-president who that day refused to block certification of Joe Biden’s election win. Some hated him, others thought he was one of them. Gallows with his name on appeared. Trump didn’t care.

Michael Flynn and Marjorie Taylor Greene, Trump loyalists on the national political stage, count themselves among the ranks of QAnon. Other politicians, like Ron DeSantis, Florida’s governor, and Kevin McCarthy, the speaker of the House, would prefer not to talk about it – but know QAnon is a source of Republican votes as well as Trump shock troops.

The politicians prevaricate. McCarthy once said there was no place for QAnon within the Republican party. Three months after that, as Sommer puts it, “he suffered a bout of selective amnesia”.

“I’m not sure what that is,” DeSantis told one reporter. In March 2022, he appointed Esther Byrd to Florida’s board of education. She had tweeted her support for the insurrection and the Proud Boys. She flew the QAnon flag on her family boat.

George Soros and Hillary Clinton, familiar boogeymen to the right, feature in QAnon lore. One early internet post from “Q”, the anonymous instigator of the conspiracy, read: “Hillary Clinton will be arrested between 7.45am-8.30am EST on Monday – the morning on 30 October 2017.”

Clinton remains free. Trump flogs Soros in fundraising emails. Meet the new antisemitism: a lot like the old version.

Some QAnon adherents contend that John F Kennedy Jr, oldest son of the 35th president, is still alive. Why is complicated but some say he is actually Q. They believe he faked his death in 1999 to avoid the cabal, which his father failed to do. Sommer describes how dozens of the faithful flocked to Dallas in 2022, convinced JFK Jr and a passel of other deceased celebrities would return. Suffice to say, they were disappointed.

Sommer also shows how the Covid pandemic breathed life into QAnon just as the movement was flailing. Adherents were losing interest. The “storm”, the moment in QAnon lore when the wicked are punished and Trump emerges resplendent in triumph, appeared to be slipping away. The chatrooms and social media accounts that doubled as QAnon conduits were narrowing.

But Covid’s reach, its origins in China and the US government’s response played into the movement’s distrust of institutions and simple fear of foreigners. And worse. Sommer records how QAnon adherents defiantly flaunted Covid public health rules, then died.

The fact that Covid mortality rates diverged between red and blue America was not a game changer. Recent revelations about US intelligence and whether the coronavirus came from a lab leak stand to bolster the fury. That the powers that be have been less than candid is disappointing but no surprise. Anger should be expected.

Forty percent of Republicans and three in eight Democrats believe the central claims of QAnon to be “very” or “somewhat” accurate. As he watches the 2024 primary calendar, Trump stokes and internalizes it all. Already, he is lobbing the words “pedophile” and “groomer” towards his main challenger, DeSantis.

Recent polls show Trump solidifying his lead. White evangelicals lacking a college degree are a key voting bloc. Trump is playing to his strength.

Sommer suggests answers to the emergence of QAnon. He acknowledges that direct confrontation is not the way to go. With organized religion in retrograde, amid a growing national malaise, the fury may be here for some time.

• Trust the Plan: The Rise of QAnon and the Conspiracy that Unhinged America is published in the US by HarperCollins