NEW YORK

"There he goes! There he goes! Follow him!"

We bounce, five ultra-Orthodox Jewish Satmars and me, through Williamsburg in a white SUV late one Sunday night in hot pursuit of Moses Friedman, the white-bearded gabbai (royal adviser) to Rebbe Zalmen. The gabbai drives his Cadillac down a tenement canyon. We tailgate him, fishtailing around corners, braking, accelerating.

The gabbai stops and squints at us in his rearview mirror.

The five Satmars, who are followers of Rebbe Aaron, who happens to be Zalmen's brother and rival, go motionless. A minute passes and the gabbai's Cadillac slips off into the night. Giggles fill the SUV. There was no point to this pursuit, other than messing with the gabbai's mind.

Now they've got a new idea. "Here! Listen to this!"

A young Satmar, his payes (curled sidelocks) shaking with excitement, cues up on his laptop a recording of Zalmen's followers, Zalis, talking to the grand rebbe. The tape allegedly reveals the Zalmenista nogoodniks tricking the senile rebbe into denouncing Aaron.

All you can really make out from the stream of Yiddish is a faint voice -- allegedly that of the grand rebbe -- asking: "Ver zeinen de menschen?" ("Who are these men?")

Where did this tape come from? Conspiratorial smiles. Husky Abe Rubin leans in and confides: "A worker in the grand rebbe's house is a real schlemiel. He recorded the conversation and sold it to us."

Richard Nixon's "plumbers," that shady crew of burglars, would have found many soul brothers among the Satmar partisans. Everyone "knows" of secret tapes, forged signatures, election chicanery and bribes. (An Aaron supporter passes along a photo of a Zalmen party in which the same face appears twice -- proof the Zalis are inflating the head count! The Aaronis dub the photo "The Two Saddams").

These are strange times for the Satmars, the world's largest and most powerful Hasidic sect.

Their leader, Grand Rebbe Moses Teitelbaum, died April 24 at 91, laid low by dementia and cancer. But the king's death brought no peace to his sons, the middle-aged Aaron and Zalmen. Their biblical battle for his crown has no clear end.

Their followers trade punches and kicks in shul, snatch kosher wine and substitute grape juice, swap slanderous rumors. Did you know David shakes hands with women? And Chaim, he talks on the phone on Shabbat? It's relayed in husky whispers, with clucks and smiles, like Merry Pranksters gone meshugeneh (crazy).

"Every party, every get-together, this is all we talk about," says one Aaroni. "It's our Mets and Yankees."

Hasidic dynasties often sunder violently. In neighboring Crown Heights the Lubavitcher Hasids wrestle with a far more irreconcilable succession problem: The biggest faction refuses to anoint a successor to Rebbe Menachem Schneerson, who died a decade ago, as they believe he was the Messiah and so is about to rise from the grave.

Moses Teitelbaum hoped to forestall such a war and ordered his sons to pick their turfs. Aaron, 57, the eldest and most scholarly of his four sons, reluctantly chose Kiryas Joel, a fast-growing Satmar shtetl of 23,000 some 90 minutes north of Brooklyn along the main caravan route to the Catskill Mountains. Then Moses appointed his milder-mannered younger son, Zalmen, 55, as rabbi of Williamsburg, the 50,000-strong shtetl in Brooklyn that remains the beating heart of Satmar. (An additional 40,000 or so Satmars live in Montreal, Antwerp, Argentina and Jerusalem). Before Moses could clearly pick his successor, Alzheimer's descended. The Satmars have no equivalent to a College of Cardinals to choose between the sons. Rabbi Isaac Wertheimer is a Zali and his explanation of succession has the simplicity of a Zen koan: "You become grand rebbe by acting grand."

So the Royal Teitelbaums wrestle for control of a kingdom vast by Hasidic standards, with more than $1 billion worth of shuls and yeshivas, social service groups and subsidized housing and mikvahs (ritual baths). Many foresee a schism.

"The Satmar are like stock market," says Avi Zupnick, a well-heeled businessman who supports Aaron, on a walking tour of the Williamsburg shtetl, 70 square blocks thick with Hasids. "We get too big" -- he snaps his fingers -- "we split!"

As with bruises and broken bones, burned cars and slashed tires, the siren song of modernity poses a danger for the Satmars. How could it not? Hasidic Williamsburg sits cheek to jowl with the hipster Williamsburg of art galleries and pierced orifices. Every Satmar man carries a cellphone and a BlackBerry. There are secret Satmar poet bloggers and a rapper or two -- Hasidic shtetls are most complicated cloisters.

Still the Satmars survive. They are enthusiastic procreators (the average mother has eight children; it is God's will) and their sect has doubled, to 120,000, in the past two decades. They grow as modern variations of Judaism shrink.

Sarala Fischer, 21, sits with Menachem, her husband, at their kitchen table in a new townhouse on a cul-de-sac up in Kiryas Joel, where Yiddish is the first language. She wears a long robe, pearl earrings, a turquoise turban and a faint, ironic smile.

"We are no angels, that's a fact -- this place is A-plus at monitoring you," she says, pushing a rocker for her 6-month-old son. "Sometimes Satmar is very, very beautiful, like family. Sometimes it's 'get out of my face,' like family. But we don't see it as restrictive -- it is loving . . . and choices are not helpful."

Menachem, only recently fluent in English, nods. "That's our barrier against leaving -- to lead a fulfilled Jewish life you need to be in the community."

Rebbe LoveKiryas Joel is celebrating the engagement of one of Aaron's dozens of granddaughters. The hubbub begins outside Yetev Lev D'Satmar synagogue, big as an airport terminal, with dozens of teenage boys in flat black felt hats and prayer shawls running up to peer quizzically into your face. Inside, the place is packed -- thousands of men in black coats and hats press together so tightly that you cross the floor with something close to a swimming motion, arms akimbo. Wood bleachers rise up each wall, and young men pack the rows, arms locked and bouncing up and down and side to side, smiling and singing prayers.

A prayer singer hops atop a 70-yard-long center table and strides toward the dais. Wearing a shtreimel, the round fur hat favored on formal occasions, the singer bows deeply before Aaron, who has been clapping rhythmically, his eyes downcast. With a thespian's timing, he looks up at the singer and smiles, then wags his hand at the young men in the bleachers. They cannot contain themselves. Their decibel level keens higher.

This is Aaron's sanctum, and these yungerleit, the young men, are his truest believers. Hasidism is a youth culture; the median age in Kiryas Joel is 15. (Married women stay home with the children; younger women are consigned to the second floor of the synagogue, behind wood-mesh screens.)

The village has the structures of municipal government -- a mayor, trustees, a constable and zoning board, all of whom are Satmars. But the rebbe is the boss of this theocracy; his is the only voice on matters spiritual. An invitation to his tisch, the Sabbath dinner on Friday, is much sought after; young men vie to clap and sing and seek advice.

Not all Satmars rely on the rebbe. But Aaron's most fervent followers call at any hour. They seek blessings for births and bris, the ritual circumcision, for engagements and weddings, surgeries and funerals. A few carry X-rays -- the rebbe might have a thought about a relative's condition or know a surgeon to call late at night. Others ask advice on a wayward child, a loan to tide through bad times, a blessing for a business venture. (It is the same in Williamsburg, where the Zalis head to Zalmen's home.)

Menachem Fischer is making his way as a home builder. Some nights he drives up the hill to Aaron's house on Sanz Court and stands in line. He is never turned away.

"I ask him if we should build, if we should buy land," says Fischer, who possesses an open face and dark, expressive eyes. "Sometimes he tells you, 'Build.' Sometimes not. Sometimes he just gives you a blessing."

The Satmars don't believe their rebbes have a pipeline to God, not precisely. But miracles surely happen. As Fischer says: "The faith we have in him, our love, gives him the power."

Out of Eastern Europe Ba'al Shem Tov was the first and greatest Hasidic rebbe, a charismatic steeped in the mysticism of Kabbalah who emerged from the pogroms and false messiahs of 17th-century Eastern Europe.

He preached that God permeates existence; by prayer and dance and love -- rather than scholasticism -- anyone can know Him. His disciples filtered across Eastern Europe, their sects taking the name of the towns they settled, the Belz from Belza in Eastern Poland, the Lubavitchers from Lubavitch in Belarus, the Bobover from the Galician town of Bobowa. The Satmars took their name from Satu Mare, the Romanian city where Joel Teitelbaum, the sect's founder, was appointed rabbi in 1934.

Within the decade, the Satmars were all but extinguished. In 1944, the Nazis marched into Hungary and deported or killed 70 percent of the Jews. Teitelbaum was shipped to the Bergen-Belsen concentration camp, only to be released in a deal the young Zionist Reszo Kastner made with Adolf Eichmann to purchase the freedom of 1,684 Jews, not least Rebbe Joel.

It was an unexpected deliverance. The Satmars are ardent anti-Zionists.

"Everyone ignores the fact that it has been these Zionist groups that . . . have violated the oath against establishing a Jewish entity before the arrival of the messiah," Teitelbaum wrote after the war. "It is because of the Zionists that six million Jews were killed."

(Arriving in Williamsburg in 1946, Teitelbaum found a hardworking Italian and Jewish neighborhood of markets and factories, dance halls and pool joints. This was not so good; it was a trayfe medina (unclean city).

Slowly, Teitelbaum built his shtetl. He encouraged his followers to make their way in the secular work world, the better to accumulate riches in real estate and the diamond trade (and B&H camera stores), and tithe money to build shuls and yeshivas. They set about pushing aside secular neighbors -- more than a few Puerto Rican and Italian homeowners tell of men in black hats and beards knocking daily at their door and offering them suitcases of cash to leave.

"It was infuriating," recalls Luis Acosta, a longtime Williamsburg activist who harbors a grudging respect for the Satmar. "They just wanted to force everyone out."

Teitelbaum established a cradle-to-grave kingdom. There are tuition subsidies and interest-free loans, and Satmar butchers give discounts to the poor. New families receive free car seats; impoverished brides get wedding dresses. Satmar bureaucrats play New York's social service agencies like a Wurlitzer organ, pulling down many state and federal grants.

But Teitelbaum brooked no compromise with modernity. He banned television and frowned on radio and novels. His fiercest sermons inveighed against the very notion of accommodation. When he died in 1979, his nephew Moses took over, running a caretaker regime until his death six weeks ago.

Boys study the Torah and, until the age of 6, speak Yiddish only. Girls are tutored in math and English and enough computer skills to make a living. (Science is an unexplored hallway; the Satmars teach nothing of physics and biology and believe the world was created 6,000 years ago.) Only 3 percent have college degrees.

On her wedding day, a Satmar woman shaves her head and dons a wig or turban for modesty. "Everything Joel said, we move not one inch," says Abe Rubin, the rotund Aaroni, holding a forefinger and thumb a centimeter apart. "We're the most ultra-, ultra-, ultra-orthodox in the world."

Zalmen is cut from his father's cloth, a careful leader who relies on the counsel of his gabbai, the white-bearded Moses Friedman.

Aaron walks a different, more charismatic path. He has a distaste for dissent. His followers have barred dissidents from a communal graveyard and shooed their children from the yeshiva.

And there are whispers of worse at the hands of his yungerleit.

"He's trying to morph his community into a more consciously Hasidic community," says Zalman Alpert, a research librarian at Yeshiva University and scholar of Hasidism. "But charismatic leaders have a way of alienating themselves, and violence has reared its ugly head."

Not So Merry Mischief Last fall, the Aaronis marched African American nightclub bouncers into the Williamsburg synagogue and punched out a few Zalis. A Teitelbaum brother, Leipa, aligned with Zalmen, kicked an Aaroni in the face at shul. Cars have been torched, one in front of Aaron's house. A convalescent home burned to the ground in a suspicious fire. As for this pugilism, Freud could nail that one. A fistfight, a yelling match, a slashed tire holds a certain adrenal attraction; the older partisans are well aware of this fact. Satmar adolescents cannot exercise or play sports. Dating is out of the question, as is masturbation, officially. Sleeping on your stomach is frowned on.

"It's a disgrace," Sarala Fischer says. "Their fistfights are not possessive of us all."

The brawling has spilled into the courts.

Not long ago, Moshe Yaakov Brach testified in state Supreme Court as an expert for the Aaronis on Satmar religious traditions. On cross-examination Brach acknowledged another expertise: swindling.

It seems he once convinced a small Wisconsin town to lend him $250,000 to build a pay-toilet factory. But he never built it.

"You didn't pay back the money until you were arrested, correct?" asked lawyer Scott Mollen.

"Right," Brach replied.

"At the time you were arrested," Mollen continued, "were you also charged with committing criminal conduct relating to the Union Carbide Company?"

Brach nodded. "Yes."

Later, Mollen asked if by chance Brach ever had escaped from a federal halfway house.

"Did not return to the halfway house," Brach replied, according to the court transcript. "Whatever."

This game-playing has infuriated the court.

"There have been many incredible and outrageous attempts by certain [Satmars] . . . to discredit, intimidate and improperly influence this Court," State Supreme Court Justice Melvin Barasch wrote in 2004. Brach has "inundated Court Administration with false, incredible stories claiming 'deals,' 'bribery' etc. involving this Court and its staff."

In private, some Satmar women sound as fed up as the judge.

"We agree not to speak of any politics at home, though the hubby's free to get all hotheaded in the synagogue," explains a Satmar woman in Brooklyn. "For all the battling, or rather precisely because of it, none of the two sons are getting very much rebbe-like respect or holy awe."

The Life So the fists fly and the lawsuits over succession grind on. But in many ways the more intriguing questions go to the mystery of this life. A secular observer wonders what keeps a Satmar tethered to this restricted world. The Satmar wonders why you wonder.

The Satmars acknowledge they cannot quite seal themselves within a 19th-century Hungarian world. A burly and amiable Satmar fishmonger aligned with his sect's most ultra-orthodox wing comes to your house to chat and at evening's end turns to your son and says: "So you like Notorious B.I.G.? Eminem and Public Enemy, they are straight-up great."

Cruise the orthodox Web sites, and you can find Hasidicrebel.blogspot.com, where a Hasid writes of reconciling doubt -- and his love of Bob Marley, Sting and Philip Roth -- with the "divine mystery" of black hat life.

"Chasids are raised with a set of powerful beliefs that leaves no room for doubt or ambiguity," he writes. "We might just be living an illusion . . . but it is a sweet illusion."

Sarala and Menachem Fischer know nothing of hip-hop or Philip Roth. Their parents arranged their marriage with the help of a matchmaker. Sarala remembers the beshow, the first date. Her intended, a young man with thick glasses and black felt hat, walks in. He can't bring himself to look at her, asking only:

"What job do you do?"

The hour crawls by. In six months they will be married.

The rabbis gave Menachem a 10-lesson course in how to live with a wife. The last lesson was sex. "I grew up in a family of boys; until four weeks before marriage I don't know the difference between boys and girls," he recalls. "I was scared!"

Sarala rolls her eyes.

"Y'know what they teach?" She imitates the Yiddish accent. " 'Vimen zar moody.' The first weeks after marriage you just sit there and want to talk and he falls asleep."

Sarala and Menachem laugh, they steal looks, they blush. "We don't believe in falling in love," Sarala says. "We believe in building love."

Outside marriage, men and women build careful walls. A woman may work for a male, but no jokes, no family talk, everything curt. On the birth of a child, perhaps a boss says mazel tov.

Shtetl life offers the love of an enveloping family. Are there headaches, too? Oy. Of course! Sarala and Menachem were not married three months when yentas (gossips) began to peer at her belly for signs of the telltale bulge.

Everyone looks superficially alike, but there are those who keep every rule, who take the ritual bath and pray for hours each day. And those who test the limits, who sneak away to a movie, surf the Net, raise a hemline, steal a touch, drink coffee on the way to shul.

Maybe a young Satmar turns on the FM in the car. Still he shares laughs and puts on his tallis and davens (bows ritually) at Friday night prayers.

"We put gate within gate within gate," Sarala says. "If we fall, we don't fall the whole way."

At her kitchen table, late into the evening, she talks of the "glass wall" that separates the Satmar women from secular women. She finds security behind that glass, a safety that saves this very bright woman in this community much confusion.

"My husband was a very simple teenager, but for me, I wondered about music, about college," she says. "If I had the opportunity to make choices, I'd probably be in Botswana somewhere wondering what to become. And it would take me 70 years to find my way home."

"Without this world," she says, "I would wander, I would fall, I would be lost."