He flashed it at me good-naturedly one afternoon on the hotel rooftop, where I had retreated to take in the view of the golden-domed shrine of Imam Ali while making calls on my Thuraya satellite phone in privacy. Safeer wanted to borrow the phone to contact far-flung relatives, and his pistol combined with his body mass made him difficult to turn down. Snatching the Thuraya out of my hands, he dialed a number in Dubai. “Hussein!?!” he screamed, bellowing into the receiver in a voice that could have stirred Imam Ali from his mausoleum. “Hussein?!?” When the 10-minute call was over, he planted a sloppy kiss on my cheek, scratching me with his sweaty beard stubble.

I had arrived in Najaf a day earlier, limping into the holy city of the Shiites in a Mitsubishi Pajero that I had rented in Kuwait and that had been acting strangely ever since I’d hit an abandoned military speed bump at 60mph on the highway north of Basra. We had taken the vehicle to a garage in An Nasiriya, a dismal town south of Baghdad where some of the worst fighting of the war had taken place, and after tightening a few nuts and bolts, the mechanic had sent us on our way. Two hundred miles later, the Pajero was stalling and bucking like a rodeo pony, drawing looks of astonishment as we navigated through crowds of Shiite pilgrims.

We found our way to the best hotel in town: the Al-Bader Palace, a gloomy dive frequented by Iranian pilgrims, located on a teeming roundabout a few minutes’ walk from the shrine. The hotel clerk grabbed my bags and led me up a dingy stairwell to a narrow chamber overlooking an air shaft, with five skinny beds lined up side by side-each one covered with a half-inch thick mattress and a pillow that appeared to be filled with sand.

At the time of my arrival early last week, Najaf–like much of Iraq–was a city caught between euphoria and fear. Three weeks after the fall of the Saddam dictatorship, Shiites from across Iraq had just finished making a pilgrimage to the shrine of Imam Hussein in nearby Karbala, a journey banned during Saddam’s time. Now they were preparing for another major festival in Najaf, commemorating the death of the Prophet Mohammed. The pilgrims had begun trickling into town the day we arrived; soon the numbers would grow to more than 1 million, a massive human wave that blocked highways, tied up traffic for miles and filled the decrepit quarter around the shrine of Imam Ali with a mass of happy humanity. At the same time, Najaf was still in shock over the slaughter that had taken place on April 10 at the shrine’s eastern gate. An angry mob had surrounded a U.S.-backed moderate Shiite leader named Abdelmajid al-Khoie, along with the shrine’s custodian–a member of the Baath party–and hacked and shot them to death, then dumped their corpses in the street.

Some in Najaf believed that the man behind the murders may have been a zealous young cleric named Moqtada al-Sadr, who had taken over the huge following of his martyred father (murdered by Saddam’s henchmen in 1999) in the weeks since the fall of the government. He moved about town in a battered Toyota surrounded by black-bearded, black-turbaned bodyguards, denouncing the American presence. Other pro-U.S. Shiite clerics had sealed themselves indoors or gone into hiding, terrified that the mobs would turn their rage against them. Najaf in these days was an unpredictable place–teetering between freedom and anarchy, elation and despair–and the week I would spend there would offer a window onto the upheaval sweeping the country.

My primary vantage point was the Al-Bader Palace, a tumbledown four-story building at the edge of the souk, a meeting place for pilgrims, businessmen, gangsters and journalists. The Al-Bader had the only restaurant in town, and the sole offering on the menu was kebab–rolls of greasy mystery meat that I somehow ate for eight lunches and dinners without doing permanent damage to my digestive tract. Located at the busiest intersection in Najaf, the Al-Bader always seemed to be near the action.

Across the street from the hotel stood a branch of one of Iraq’s largest banks, where agitated crowds formed each morning, attempting to exchange 10,000-dinar notes for 250-dinar bills: merchants had refuse to accept the larger denominations since a spate of bank robberies swept the country just after the regime’s collapse. The bank offered only 8,000 dinars for every 10,000-dinar note, infuriating people such as my translator, an English teacher from Basra whose entire salary had been paid with the larger bills. “This is a nation of Ali Babas,” he told me, referring to the famous thief of Arab lore. Nearby sprawled the Shiite cemetery, the largest in Iraq; on my second night in town members of Najaf’s new police force chased four suspects in the Khoie killing into the graveyard, engaging them in an hour-long gunfight that echoed through the city. All the suspects, it turned out, were followers of the cleric Moqtada al-Sadr.

The hotel’s main attraction was the gargantuan Safeer, a relative of the owner, who guarded the hotel and its parking lot at night. Chain-smoking “Pine” Iraqi cigarettes and hustling journalists for money and phone access, Safeer proudly displayed a laminated paper badge given to him by the newly formed Najaf city council. It identified him as a newly recruited member of the municipal police force–a measure of how desperate the situation had become in the holy city of the Shiites.

As the Prophet Mohammed’s death anniversary approached, moving around Najaf became nearly impossible. Hundreds of thousands of pilgrims filled the town, flooding the muddy warrens around the shrine of Imam Ali. Boisterous youths carried green and black Shia flags–similar to those borne by the celebrated imam and his son Hussein into battle in seventh-century Iraq-through the streets, joining a throng of donkey carts, female pilgrims in black chadors and vendors of coconut cakes, incense, rosary beads, apples, prayer rugs and a thousand other items. On the day of the festival, Safeer had the idea, deeply unwise in retrospect, to visit the headquarters of Moqtada al-Sadr, one block from the shrine. We set out from the hotel at 9 a.m. in the crippled Pajero, and within a 100 yards we were engulfed by a sea of humanity. The mob surged around the vehicle, banging their fists against the windows in what first seemed an exuberant greeting, but quickly turned threatening. The driver hunched over the steering wheel, nervously inching forward; children darted in front of the Pajero, narrowly avoiding being crushed beneath the massive tires. I begged the driver to be careful; all it would take was one child to fall under the wheels to turn the mob against us. Finally we stopped dead in the center of an alley, surrounded by a solid mass of singing, dancing, screaming celebrants. Then Safeer came to the rescue. The 300-pound bodyguard climbed out of the Pajero, elbowed his way to the front of the car, and cleared a path through the sea of pilgrims. Inch by inch, foot by foot, we painstakingly made our way to the entrance of Moqtada al-Sadr’s alley. The holy man, it turned out, wasn’t home.

I caught up with the cleric two days later at the Mosque of Kufa, the site of the murder of Imam Ali, the Prophet Mohammed’s son-in-law and the spiritual forefather of the Shiites. The mosque was the same place from which Sadr’s father, Mohammed Sadeq al-Sadr, gave fiery speeches after Friday prayers in which he called for freedom of religion and demanded that the regime release political prisoners. In the spring of 1999, after defying warnings from Saddam’s security agents to stop the speechifying, the elder Sadr was gunned down along with two of his sons in his car in Najaf. Four years later his second-youngest son had emerged as one of the most visible new leaders in the country, with a built-in following of thousands of his father’s supporters. Sadr was making a bid to control the keys of the Shrine of Imam Ali, which would give him access to millions in donations left there by Shiite pilgrims. He was also criticizing the American presence in the country, causing worry to the U.S. nation builders in Iraq who hoped to empower pro-Western leaders.

Crossing the vast outdoor courtyard of the mosque, I hopscotched across a sea of worshipers and prayer mats and made my way to the marble-columned inner sanctum, from which Sadr would deliver his address. Sadr’s bodyguards escorted me to a vantage point beside the podium. Moments later the cleric arrived. A broad-faced man with a thick black beard and intense eyes, he wore, over his black dishdasha, a white burial shroud, a tribute to his murdered father. The crowd rose to its feet; individual worshipers sang out Sadr’s praises. The cleric’s speech was surprisingly humdrum–a call to ban alcohol in Iraq, a demand that women dress modestly and refrain from wearing jewelry–but the 30,000 followers seemed overjoyed simply to hear him speak. After prayers I followed Sadr down a corridor toward his waiting Toyota, only to be swept aside by a groping mob. The emotional catharsis, after 30 years of brutal repression by Saddam and his gang, was astonishing to observe. But the ripples of violence lurking just beneath the surface were impossible to miss.