Missy Sims carefully picked her way through a field of ruined tombs in central Puerto Rico, in a cemetery where walls of water from Hurricane Maria had smashed open some coffins and sent others careering into a nearby stream.

Six years later, the burial place in Lares, where more than 1,700 graves were damaged, is still shattered.

“This is apocalyptic, end of the world, end of times stuff,” said Ms. Sims, an attorney who is representing 16 Puerto Rican municipalities that are seeking to hold the fossil fuel industry responsible for the damage caused by a series of storms, including Maria.

Ms. Sims wiped away a tear as she surveyed the broken graves and absorbed the pain of the grieving families. But she also vowed to hold those responsible to account.

Ms. Sims, 54, may be the most surprising legal figure to emerge as the world grapples with the devastating impacts of a warming planet. An Armani-and-Rolex wearing observant Catholic from a small Midwest town who talks to God as she mulls her complex legal cases, Ms. Sims is also a constant TikTok poster whose dog has more followers than some celebrities.

And she is now the singular force behind a creative legal gambit to make oil and gas companies pay for the devastation being wrought by climate change in Puerto Rico. Her strategy is being carefully watched by the fossil fuel industry and environmental groups as well as other lawyers and municipalities.

The lawsuit she filed in November goes after a who’s who of the fossil fuel industry — Exxon Mobil, Chevron, Royal Dutch Shell, BP and others. Ms. Sims argues that since 1965, those companies have produced 40 percent of global greenhouse gas emissions, while at the same time colluding to deceive the public about the disastrous consequences of their actions.

The case is part of a new wave of litigation targeting oil, gas and coal companies over climate change, which is driven by the burning of their products. But it stands out in two significant ways.

It was the first to allege that, by downplaying the effects of global warming for decades, the fossil fuel companies violated the Racketeer Influenced and Corrupt Organizations Act, which was originally designed to crack down on organized crime. So-called RICO charges expose the defendants to potentially huge financial damages and open up a new front in their growing legal challenges.

The case was also the first to request damages from a specific weather event. In her 247-page complaint, Ms. Sims notes that scientific studies have shown that man-made global warming made the 2017 hurricanes more severe, causing Maria to rapidly intensify in a way that killed thousands and inflicted more than $100 billion worth of destruction on Puerto Rico. It was the worst storm to ever hit the island.

Exxon and ConocoPhillips declined to comment. In a statement, Shell said, “We do not believe the courtroom is the right venue to address climate change, but that smart policy from government and action from all sectors is the appropriate way to reach solutions and drive progress.”

If the companies were found liable, the potential damages could run into the hundreds of billions of dollars, legal experts say.

“That’s why the companies are so afraid of these cases,” said Richard Wiles, president of the Center for Climate Integrity, a nonprofit organization that is helping garner support for the Puerto Rico case. “If they have to pay for the damages they caused, the costs get out of control really fast.”

‘God’s Work’

This isn’t the first time Ms. Sims has sued Exxon.

She got her start as an associate at a small-town firm in central Illinois run by an accomplished municipal lawyer who would start each workday by leading the office in prayer. That suited Ms. Sims.

“He didn’t try to cram it down anybody’s throat,” Ms. Sims said. “He literally was just, ‘Hey, let’s do God’s work today.’”

Ms. Sims soaked up local code and helped communities prosecute people who wouldn’t clean up after their pets, residents who didn’t have their trailers on foundations and landowners who wouldn’t cut their weeds.

After several years, the mayor of DePue, a tiny village on a lake in northern Illinois, told Ms. Sims about a much more serious nuisance. A former industrial site was polluting the community, and no one would clean it up.

The site, a shuttered zinc smelting facility that once helped make film for Hollywood, had closed in 1989. But hazardous amounts of lead, mercury, cyanide, and cadmium remained in the ground. When it rained, puddles turned bright blue from the heavy metals, and local residents were getting sick.

The village of 1,600 people had one of the highest rates of multiple sclerosis in the country, and residents suspected elevated cancer rates were also tied to the site. Yet after more than a decade of trying, the community couldn’t get the site’s current owners, which included Exxon, to pay for the cleanup.

“The town was just sick,” Ms. Sims remembered. “They were sick of the inaction by the regulators, and by these multinational companies.”

Determined to come up with a way to help, Ms. Sims went for an evening jog. It is on these long, meditative runs that she says she talks with God.

“I get along with the Holy Spirit and I’m just like, ‘Help me. Help me help these people,’” she said. “And he said, ‘Fine them.’”

Ms. Sims prayed on it. “I fine people every day for having dog poop in their yards, tall weeds, broken windows,” she remembered thinking. This wasn’t so different, she reckoned.

The next day, she pitched her boss on the idea. He was in. And in 2006, Ms. Sims helped the village sue Exxon and the site’s other owners — for littering.

The companies appealed, and the suit was initially dismissed on technical grounds. But Ms. Sims filed an amended complaint and the case started making its way through the court system. Years of procedural maneuvers followed, and in 2013, the village settled with Exxon and the other owners for almost $1 million. Exxon did not respond to a request for comment.

It wasn’t a lot of money, given the size of the problem, yet it set an important precedent. With her novel legal strategy, Ms. Sims had brought an oil giant to the bargaining table.

“Other law firms were like, ‘How did you do that?’” she said.

Even before that settlement, Ms. Sims had taken on her next big case. An oil refinery in another small village, Roxana, Ill., had polluted the groundwater with benzene, a carcinogen, and the site’s owners, Shell and ConocoPhillips, wouldn’t clean it up.

Ms. Sims helped Roxana file 230 tickets against each company for littering in traffic court, setting off another round of onerous litigation for some of the country’s biggest fossil fuel companies. Once again, they settled. In 2017, Shell and ConocoPhillips agreed to pay almost $5 million.

For Ms. Sims, it was validation of her hunch that the smallest of towns could take on the world’s biggest companies.

In short order, Ms. Sims joined Milberg, one of the largest class action firms in the world.

The firm was working on bringing cases against companies over the opioid crisis, and sent Ms. Sims to Puerto Rico in 2017 to help build a case on behalf of local governments struggling with the fallout from drug addiction. Months later, Hurricane Maria hit.

After the storm, Ms. Sims returned to continue her work and was stunned. “I could not believe the devastation,” she said. “Everything was leveled. It looked like a bomb had gone off. It looked like Hiroshima.”

As she drove across the island to meet with local officials about the opioid crisis, it occurred to her that Puerto Ricans were now suffering at the hands of another set of corporations. Fossil fuel companies had warmed the planet and misled the public about global warming, making billions along the way. It wasn’t so different from what had happened in DePue and Roxana, she thought.

Then, she said, God told her to sue Exxon again.

“The Holy Spirit tells me what to do,” she said. “This bomb that went off here was climate change related. We just need to prove it.”

‘I Hold Them Responsible’

The morning after Ms. Sims visited the cemetery in Puerto Rico, she was up at dawn preparing for the day. With a recording of the Bible playing on her iPhone, she applied her makeup and donned a pink corduroy suit and a silk Gucci scarf, then marched out the door carrying a large Fendi handbag.

“It’s a show of respect and confidence,” she said about the meticulous care she takes with her appearance. “I’m meeting people all the time, and you want them to know that you’re taking them seriously. That’s the way I was raised.”

An hour later, she arrived in Caguas, a small city nestled in a lush valley south of San Juan. Accompanied by an associate from her firm, Ms. Sims greeted several city officials and unspooled the plan of attack.

She described how starting in the 1980s, companies including Exxon understood that fossil fuel emissions would rapidly heat the planet, but began a coordinated effort to conceal that information from the public. How they waged a sophisticated lobbying effort to block the regulation of emissions. How they sowed doubt around the increasingly conclusive science of climate change.

And how Shell produced an eerily prescient memo in 1998 that predicted that a “series of violent storms” would hit the Eastern coast of the United States, and that following the storms, there would be a “class-action suit against the U.S. government and fossil-fuel companies on the grounds of neglecting what scientists (including their own) have been saying for years: that something must be done.”

As the meeting concluded, the city attorney, Monica Yvette Vega Conde, said that regardless of the outcome, it was important to bring the case.

“Mostly we want to make that statement,” she said. “It’s real, it’s here and it happened to us.”

Afterward, Ms. Sims indulged in a ritual that keeps her grounded in between emotional meetings. She stopped for ice cream. Eating a Nutella-flavored Frosty from Wendy’s, Ms. Sims checked TikTok and showed off a new viral video of her dog, GeorgyGirl, who had amassed 2.2 million followers.

From Wendy’s, she headed to the coastal city of Loíza, another of the 16 municipalities that brought the case. Hurricane Maria sent ocean water flooding into its streets, ripped the roofs off buildings and tore up roads. Six years later, City Hall was still in tatters. Skylights were broken, blue tarps covered the roof and the walls were buckled.

The mayor, Julia María Nazario Fuentes, listened to an update on the case and then escorted the lawyers to the shoreline, where a sidewalk had crumbled into the sea in 2017 and remained nothing more than a pile of rubble.

Hurricane Maria was made more powerful and dropped more rainfall because of man-made climate change, studies have shown. Hurricanes are becoming more destructive as the atmosphere and water temperatures rise because of global warming, scientists say. And the waters around Puerto Rico have warmed substantially in recent years, leading to the rapid intensification that made the storms so powerful.

“That warmer water around Puerto Rico, that was the rocket fuel,” Ms. Sims said. “That’s the key to the case.”

As the mayor stood on her city’s ruined beachside promenade, she said the more she learned about the fossil fuel companies named in the complaint, the angrier she got.

“I hold them responsible for everything,” the mayor said. “Human beings have to be more responsible in protecting what God gave us as a gift.”

‘Settle With the World’

When Ms. Sims is not in Puerto Rico, she is at home in Princeton, Ill., where she lives alone, not far from where she grew up, and not far from DePue. Working from an antique wooden desk with four computer monitors, she pores over evidence and refines her case. When she needs a break, she goes into the backyard and films her dog frolicking in the swimming pool.

By early next year, it should be clear whether the case against the fossil fuel industry clears enough legal hurdles to move toward trial.

Ms. Sims doesn’t expect a settlement, given the sweeping nature of the charges. “If they settle with us, they will have to settle with the world,” she said.

Legal experts are watching the case closely. Robert Brulle, a visiting professor at Brown University who has researched the efforts by fossil fuel companies to mislead the public, said he believed Ms. Sims had made too much of some details in the Puerto Rico complaint, but that the overall argument was sound.

“I can tell you that these companies worked together to stop climate action,” he said. “Whether that passes legal muster, I don’t know.”

Senator Sheldon Whitehouse, Democrat of Rhode Island and that state’s former attorney general, is also paying attention. He has compared the fossil fuel industry’s tactics to the tobacco industry’s efforts to downplay the health effects of smoking.

Just as tobacco companies faced RICO charges and were ultimately found guilty in federal court, Senator Whitehouse said oil companies were vulnerable to the kind of racketeering case that Ms. Sims has now brought on behalf of Puerto Rico.

“The common thread there is that somebody is willing to lie for money,” Senator Whitehouse said.

Already, the Puerto Rico case is having an impact. Just days after Ms. Sims returned from her trip, the city of Hoboken, N.J., amended its complaint against big oil companies to include state RICO charges.

And in June, lawyers in Oregon sued fossil fuel companies over a deadly heat dome in 2021, the second time, after the Puerto Rico case, that lawyers have brought claims against oil and gas companies for damages from a specific weather event.

From her home office, Ms. Sims applauded the developments in New Jersey and Oregon. It was more validation, she said, that she was doing God’s work.

“I believe the Holy Spirit is my co-counsel,” she said. “He’s never steered me wrong.”