In the early morning hours of July 3, one of the two top commanders of Al Qaeda in Syria summoned me from my jail cell. For nearly two years, he had kept me locked in a series of prisons. That night, I was driven from a converted schoolroom outside the eastern city of Deir al-Zour, where I was being held, to an intersection of desert paths five minutes away. When I arrived, the commander got out of his Land Cruiser. Standing in the darkness amid a circle of men draped in Kalashnikovs, he smiled. “Do you know who I am?” he asked.

“Certainly,” I said. I knew him because he visited me in my cell once, about eight months earlier, and lectured me about the West’s crimes against Islam. Mostly, however, I knew him by reputation. As a high commander of the Nusra Front, the Syrian affiliate of Al Qaeda, he controlled the group’s cash and determined which buildings were blown up and which checkpoints attacked. He also decided which prisoners were executed and which were released.

He wanted to make sure I knew his name. I did, and I repeated it for him: Abu Mariya al-Qahtani. “You are our Man of Learning,” I added, using the term — sheikhna — that his soldiers used to refer to him.

“Good,” he said. “You know that ISIS has us surrounded?”

I did not know this.

He shrugged his shoulders. “Not to worry. They won’t get me. They won’t get you. Everywhere I go, you go. Understand?” I nodded.

We drove to a residential compound next to an oil field near the Euphrates. For the rest of the night, I watched as some 200 foot soldiers and 25 or so religious authorities and hangers-on from the Afghan jihad prepared for their journey.

There were bags of Syrian pounds to stuff into the cabs of Toyota Hiluxes, boxes of stolen M.R.E.s to load onto the truck beds and suitcases and water coolers to fit in beside them. And there was the weaponry: mortars, rockets, machine guns, feed bags filled with grenades and bullets, stacks of suicide belts.

By 4 in the morning, the packing was done. At dawn, the commander drove to the head of the column of Hiluxes and fired his handgun into the air. Within seconds we were gone, flying over the sand. There are roads in this part of Syria. We didn’t use them.

Image A scene from a Nusra Front video of Padnos in Syria. Credit... Associated Press

I was now 20 months into my life as a prisoner of the Nusra Front: the abrupt departures, the suicide belts, the mercurial behavior of the Man of Learning, the desert convoys, the way I might be shot or spared at any moment — this was my world. I was almost used to it.

In October 2012, however, when I was first kidnapped, I used to sit in my cell — a former consulting room in the Children’s Hospital in Aleppo — in a state of unremitting terror. In those first days, my captors laughed as they beat me. Sometimes they pushed me to the floor, seized hold of a pant leg or the scruff of my jacket and dragged me down the hospital corridor. If someone seemed to take an interest in the scene, I would scream: “Sa’adni!” (“Help me!”) The onlookers would smirk. Sometimes they called out a mocking reply in English: “Ooo, helb me! Ooo, my God, helb me!”

Because there was no bathroom in my cell, I had to knock on the heavy wooden door when I needed the toilet. Often, the guards wouldn’t come for hours. When they did, they would bang on the door themselves. “Shut up, you animal!” they would say.

The cruelty of my captors frightened me, but my bitterest moments in those early weeks came when I thought about who was most responsible for my kidnapping: me.

I believed I knew my way around the Arab world. In 2004, when the United States was mired in the war in Iraq, I decided to embark on a private experiment. I moved from Vermont to Sana, the Yemeni capital, to study Arabic and Islam. I was good with languages — I had a Ph.D. in comparative literature — and I was eager to understand a world where the West often seemed to lose its way. I began my studies in a neighborhood mosque, then enrolled in a religious school popular among those who dream of a “back to the days of the prophet” version of Islam. Later, I moved to Syria to study at a religious academy in Damascus. I began to write a book about my time in Yemen — about the mosques and the reading circles that formed after prayer and the dangerous religious feeling that sometimes grew around them.

Image Padnos in 2005 in Yemen, where he studied Arabic and Islam. Credit... From Theo Padnos

At the beginning of the Syrian civil war, I wrote a few articles from Damascus, then returned to Vermont in the summer of 2012. Just as the Islamists were beginning to assert their authority in Syria, I began pitching articles to editors in London and New York about the religious issues underlying the conflict. By now, I could recite many important Quranic verses from memory, and I was fluent enough in Arabic to pass for a native. But these qualifications mattered little. The editors didn’t know me; few bothered to reply. Perhaps, I thought, if I wrote from Syria itself, or from a Turkish town on the border, I’d have better luck. On Oct. 2, 2012, I arrived in Antakya, Turkey, where I rented a modest room that I shared with a young Tunisian. I tried pitching the editors again. Still nothing. I began to despair of publishing anything and cast about for something else to do. Should I try teaching French? I wondered. Coaching tennis?

I spent my afternoons in Antakya walking up a mountain on the outskirts of the city and looking across into Syria. By this time, despite its aggressive bombing campaign against the opposition and the civilian population, President Bashar al-Assad’s military government was losing ground. The international community condemned Assad for his actions against civilians, but none that joined in the censure, including the United States, intervened militarily. On TV, Islamic preachers railed against the Syrian government: Those who helped it would have their flesh cut into bits, then fed to the dogs. The government, for its part, warned that in areas of the country under opposition control, fanatical Islamists, possibly in the pay of the Israelis, were sneaking in from Iraq and Libya. The main opposition group, the Free Syrian Army, founded by former Assad generals and considered moderate by many in the West, had taken over the two most important border crossings north of Aleppo.

One day as I walked up the hill outside Antakya, an idea for an essay came to me. Anyone who has lived in Syria knows how bitter the divides are between the pious and the secular, the Assad loyalists and the dissidents, the well connected and those who struggle to get by. It would be impossible to plot these divisions on a map, because they often run through families, even individuals. Nevertheless, by the autumn of 2012, a traveler might have oriented himself by them: Most who lived east of the mountain chain that runs from the city of Homs toward the Turkish border were Sunni opponents of the government; most who lived in the mountains or to the west were Alawite supporters of Assad.

As I walked, I envisioned myself traveling along these fault lines. I would stop into villages and interview people, telling the story of a nation with many identities, dissatisfied with them all, in trouble, wanting help. In the background would be a narrator in a similar situation.

My experience in Arab countries ought to have given me pause. After I published my Yemen book, I changed my name from Theo Padnos to Peter Theo Curtis, worried that the book might make reporting from the Middle East difficult. I knew how Westerners were often viewed. But I had done all my studying under the eye of military governments, in places where the secret police listened to every word uttered in every mosque. I had never set foot in a region where only a militant Islam held sway. Things are different in such places. Almost immediately, I fell into a trap.

One afternoon in Antakya, I met three young Syrians. They seemed a bit shifty, but not, as far as I could tell, more militantly Islamic than anyone else. “Our job is to bring stuff from here to the Free Syrian Army,” they told me. They offered to take me with them. Thinking I’d be back in a few days, I told no one, not even my Tunisian roommate, where I was going.