On December 21st, Jane Fonda turned eighty-two, and it might have been her best birthday yet. Since October, Fonda has been getting herself and her celebrity pals arrested as part of an ongoing campaign to raise awareness of climate change, through acts of civil disobedience. Last Friday, on the eve of her birthday, she vowed to mark her advancing age by bringing eighty-two people along to get arrested with her. In fact, she exceeded expectations, and a hundred and thirty-eight people were arrested in total.

The crowd on that Friday included Catherine Keener, Gloria Steinem, the labor leader Dolores Huerta, the labor activist Ai-jen Poo, the Buddhist teacher Roshi Joan Halifax, and several of Fonda’s relations by marriage and ex-marriage, including Laura Turner Seydel, a stepdaughter from Fonda’s marriage to Ted Turner, and Seydel’s mother-in-law, Pat Mitchell, who is herself an author and activist. Diane Lane, Sally Field, Sam Waterston, and Rosanna Arquette have all been arrested with Fonda. This Friday, Lily Tomlin, Fonda’s co-star on the Netflix comedy “Grace and Frankie,” was arrested without Fonda. (Fonda chose not to get arrested this week because her record of prior arrests, for which she has an upcoming court hearing, could have landed her thirty days in jail.)

It is easy to ridicule Hollywood celebrities when they dip into the political arena. Critics—not least of them the vituperator-in-chief—have accused Fonda of getting arrested as a publicity stunt. “She’s always got the handcuffs on. Oh, man, she’s waving to everybody with the handcuffs,” President Trump said last month, at a rally in Louisiana.

This, Fonda retorts, is precisely the point.“Publicity stunt?” she said last week, during an appearance at the National Press Club. “I have gotten a lot of publicity because I’m a celebrity, you know. That’s why I’m doing it. If you’re a celebrity, you have a responsibility to use that celebrity. Especially when the future of mankind is at stake.”

The movement is known as Fire Drill Fridays, a name that conveys both the urgency of the climate crisis and the military precision behind the operation. Since September, Fonda has been living and working out of a hotel in Washington, near the White House. Although she has a small staff, she handles many of the details herself. A team of lawyers advises her on how to break the law just enough to be arrested but not enough to go to jail.

There are slipups, however. Fonda spent a night in the D.C. Central Cell Block after a protest on November 1st, and was confined to a cell with a hard metal cot and cockroaches scurrying nearby. It was a challenging experience for an octogenarian, albeit one who is as physically fit as you might expect a former workout guru to be. “It was hard on my eighty-two-year-old bones,” Fonda told friends.

Another obstacle is that police are not always obliging when Fonda tries to get collared. On November 8th, Fonda and friends spent hours sitting in the driveway to the White House. The Secret Service ignored them. “They just wouldn’t arrest anybody,” Ira Arlook, a fellow-activist who is serving as a spokesman, said.

A friend of mine, who is also friends with Fonda, invited me to join last weekend’s events, which gave me a sense of how artfully the climate protests and ensuing arrests are choreographed. The activities began with Fonda hosting a Thursday-evening Webcast with activists and climate experts. These “teach-ins,” as she calls them, are designed to give the movement intellectual heft beyond the usual protest sloganeering. Each week has a different theme. The session I attended was devoted to health, with a discussion of air pollution and other consequences of climate change.

The next morning, we convened at 9:30 A.M., in a church basement near Capitol Hill, for a briefing on the logistics of getting arrested: wear layers, comfortable shoes, and something red. Don’t bring too many possessions that will need to be catalogued by police. Do bring fifty dollars in cash—the fine for most acts of civil disobedience in Washington, D.C.—and a valid government I.D.

“It’s basically a parking ticket,” an organizer named Samantha Miller reassured the future D.C. lawbreakers, most of them first-timers. “It’s not on your record. You can go to law school. I taught in public school with this kind of arrest.”

After the 2016 election, Fonda was initially optimistic that Trump could be flattered into taking on the cause of battling climate change. She wanted to invite several “voluptuous” female activists (including the environmentally minded actress Pamela Anderson) to brief Trump on the dangers of relying on fossil fuels. Fonda spoke by phone to Jared Kushner, who told her to speak to Ivanka Trump, who laughed at the idea and said she’d follow up. Fonda never got to meet with Trump.

Out of this rebuff grew anger and then determination. Fonda decided to step up her game and try civil disobedience. “Activism is the antidote to despair. Better than Prozac,” she said at the National Press Club. “It lifts you out of despair when you align yourself with our deepest values.”

Fonda initially wanted to pitch a tent on the National Mall, but she was told that she’d be immediately removed. She learned that high-school students, inspired by the Swedish climate crusader Greta Thunberg, were holding regular Friday protests, and asked Greenpeace how she could join in.

“She didn’t want it to be, like, ‘The movie stars are here. Get out of the way kids,’ ” Annie Leonard, the executive director of Greenpeace U.S.A., said. “She was hungry to learn.”

The high-school students were eager for help. Jerome Foster, a seventeen-year-old senior at a charter school in Washington, D.C., had been demonstrating every Friday, with other students, and getting little attention for his trouble. With Fonda, “It went mainstream,” Foster said.

Around 11 A.M. on Friday morning, the demonstrators climbed out of the church basement and headed to the Capitol. Fonda wore her protest uniform—a fire-engine-red wool coat, purchased at Neiman Marcus—which, because of her objections to consumerism, she vows will be the last item of clothing that she will ever buy. Her V.I.P. guests also wore red, and marched with her arm in arm, behind a phalanx of security guards whose main purpose was to keep them from colliding with an expanding scrum of television cameras.

After two hours of speechifying, songs, and chants on the southwestern lawn of the Capitol, Fonda rallied the troops for the next step. “We’ve done what we can within the confines of democracy,” she intoned. “Now we are going to commit civil disobedience.”

The group marched a few blocks to the Hart Senate Office Building. The security guards at the entrance seemed both unsurprised and uninterested by the procession of celebrities coming through the metal detectors, opening bags for inspection. Once inside, Fonda and her V.I.P.s seated themselves in the center of the atrium, up against an Alexander Calder sculpture, where they continued singing and chanting. “This is what democracy looks like!” they shouted. “What do we want? A Green New Deal. When do we want it? Now!”

Senate staff leaned over the balconies to take photos. The Capitol Police stood by, holding coils of plastic handcuffs.