Matthew Schrier was helpless. An American photographer held in a rebel-controlled prison in the Syrian city of Aleppo, he and a fellow prisoner had been caught trying to gouge a hole in their cell’s wooden door. The captors took his cellmate, he said, beat him, and brought him back with blood-streaked ankles and feet.

Then it was Schrier’s turn.

Wearing masks, his jailers led him out, sat him down and forced a car tire over his knees. They slid a wooden rod behind his legs, locking the tire in place. Then they rolled him over. Schrier was face down on a basement floor, he said, legs immobilized, bare feet facing up.

“Give him 115,” one of his captors said in English, as they began whipping his feet with a metal cable.

When the torture ended, Schrier could not walk. His captors, he said, dragged him to his cell. He remembers their parting phrase: “Have you heard of Guantanamo Bay?”

For seven months, Schrier, 35, was a prisoner in Syria of jihadi fighters opposed to President Bashar Assad. Held in bases and prisons run by two Islamist rebel groups, he said, he was robbed, beaten and accused of being a U.S. spy by men who then assumed his identity online.

His captors drained one of his bank accounts. They shopped in his name on eBay. They sent messages from his email account to his mother and his best friend assuring them he was fine, but had extended his trip to do more work.

“I’m doing good man,” read an email to the friend Feb. 2. “I have access to Internet for like 5 minutes or so, and I will not be able to log in my email for at least the next few weeks.”

Schrier escaped July 29, he said, by squeezing out of a basement window and wandering, in shoes too small and with the long beard he had grown in captivity, through Aleppo until he found other rebels.

These men protected him and drove him the next day to Turkish authorities at the border. U.S. diplomats soon whisked Schrier away.

Now in the United States, Schrier has returned with a firsthand account of the descent by elements of the anti-Assad opposition into sanctimonious hatred and crime. His experience reflects the deteriorated climate for foreigners and moderate Syrians in areas subject to the whims of armed religious groups whose members roam roads, man checkpoints and occupy a constellation of guerrilla bases.

Schrier’s detention is one of more than 15 cases of Westerners, mostly journalists, being abducted or disappearing in Syria this year. The victims range from seasoned correspondents to new freelancers, like Schrier, who was covering his first war.

Some were abducted in 2012, others a few weeks ago. Many are thought to be held by two groups aligned with al-Qaida. At least one is believed to be a captive of Assad’s intelligence services.

For many cases there are few leads. The victims have vanished — a pattern that makes Schrier’s account exceptional and rare.

His experience also suggests the difficult choices for foreign governments that in principle support the rebels’ goal of overthrowing a dictatorship accused of using chemical weapons against civilians, but in practice fear aiding opposition factions that embrace terrorist tactics, intolerant religious rule or the same behaviors — abduction, torture, extralegal detention — that have characterized the Assad family’s reign.

Schrier said his captors were mostly members of the Nusra Front, a group aligned with al-Qaida and designated a terrorist organization by the United Nations and the United States.

But as he was moved from prison to prison, he said, he and his main cellmate, another American, were also held by a unit of Ahrar al-Sham, an Islamist group under the Supreme Military Council, a rebel structure recognized by Western and Arab governments.

Kidnapped from a taxi

When he set out for Syria last year, Schrier was new to war photography. Born in Syosset, N.Y., he had attended film school at Hofstra, not found a job in his field and opted to work for nearly a decade in the health care industry, negotiating rates and claims.

The travel and artistry in photography appealed to him, as did the chance at a fresh start.

“I wanted to enjoy my work for a change,” he said.

His plunge into the story was swift. He traveled in November from New York to Turkey and Jordan, where he photographed convalescing rebels and ventured across the border to an encampment of displaced Syrian families.

After an activist offered to take him to Aleppo, Schrier returned in December and was brought to a small rebel group fighting in a neighborhood and at the siege of an air force intelligence compound.

Schrier spent 18 days in Syria. His photographs were strong, he said. He was eager to return to Turkey and publish them.

But there was a complication. His expected driver did not arrive. After waiting for more than a day, his hosts arranged a taxi with a driver they said he could trust.

Their ride out began at midday Dec. 31. As they left Aleppo, rebels halted the taxi at the Sheikh Najjar industrial area, through which journalists frequently passed.

They forbade the taxi from crossing. The driver tried a route through Muslimiyah and was passing a recently captured military school, Schrier said, when a silver Jeep Cherokee forced the taxi to stop.

At least three men stepped out. One wore a black scarf over his face.

They escorted Schrier out.

“They were so nonchalant,” he said. “They didn’t point a gun at me and moved me very gently.”

Schrier said he expected that they would look at his photographs, confirm his work and release him. They directed him to the back seat of their SUV, pulled his knit cap over his eyes, leaned him forward and pressed a rifle muzzle to his head.

His captivity had begun.

(The driver later resurfaced with widely shifting tales of what had happened, according to people familiar with his accounts. Schrier said the man probably participated in his abduction.)

The kidnappers drove to a compound in Aleppo and moved Schrier to a basement. They were incongruously polite. When he was offered tea, an elderly man warned him the glass was hot.

Someone handed Schrier his iPhone and asked him for its security code, so they could read his call log, contacts, text messages and email archives.

One man, whose name Schrier learned was Mohammad, spoke broken English and gave him a nickname: Juma, the Arabic word for Friday. A man who used the name Abdullah arrived.

“We have information that there are CIA agents in the area,” he said.

Schrier said he risked an argument.

“My socks don’t match and you think I’m in the CIA?” he said.

His captors put him in a lightless room. Schrier paced — 22 foot lengths one way, 12 the other.

Repeated interrogations

The next day, Jan. 1, Schrier heard other prisoners screaming while being beaten. The sounds continued intermittently for hours.

“I was just pacing back and forth waiting for my turn,” he said.

When his captors came for him, they told him they had examined his photographs. Schrier explained his work and gave references among the rebels.

Abdullah said that if his story was accurate they would release him.

Schrier waited several days. Guards brought him food and water, and escorted him to a spotlessly clean toilet. They sometimes joked, he said, calling him Juma playfully.

On the fifth day, he said, another jailer appeared holding Schrier’s credit cards and demanding his PIN codes.

By now, Schrier said, he worried that keeping calm might convince his jailers that he had training. He pounded on his cell door and shouted. Abdullah arrived and told him he was in an Islamic court.

He asked what the charges were. Abdullah would not tell him.

Instead, Schrier said, he suggested “business propositions,” including that Schrier help solicit a $3 million ransom from a U.S. embassy in exchange for a 5 percent cut, or that Schrier agree to be a courier and transport materials for his captors’ group.

Abdullah put him back in his cell. Schrier said he banged on the door until Abdullah returned, angry.

“In your country you have a saying: You are innocent until proven guilty,” Abdullah said. “Here we have the opposite. You are guilty until proven innocent. We do not know who you are.”

A fellow American

Later that night the guards moved Schrier to a cell with many prisoners, including Alawite soldiers and officers he would eventually befriend.

In late January guards brought Schrier to a different cell. Inside, Mohammad said, was another American.

Schrier looked in and could not believe that the man was a Westerner. He was filthy, with a long unkempt beard. Mohammad told Schrier to move in and shut the door.

“Why do they have you?” Schrier asked.

The man swore in English and said he was accused of being in the CIA.

His lot was growing bleaker. His jailers discovered gouges on the cell door Feb. 6. They tortured the two Americans as punishment and afterward beat him intermittently, he said. Sometimes they zapped him with a Taser.

His captors replied to his mother Feb. 10.

“Hi mom, sorry for not giving news before,” the email read. “I’m working a lot here and having a lot of fun, think I’ll stay here for a while.”

As the weeks passed the captives were moved between makeshift jails, in and near Aleppo, and sometimes kept with more than 15 other prisoners. Defying the clichés of prison narratives, he said, his relationship with his cellmate soured and the two quarreled.

In March a Moroccan man who had lived in the United States was put in their cell, too. The man became abusive, Schrier said, taunting the Americans and once beating Schrier’s cellmate, bloodying his eye.

Schrier converted to Islam in March, he said, which improved his relations with the kidnappers and brought an added benefit: His jailers gave him something to read, an English-language Quran.

In April, he said, the prisoners were moved to a rural villa, also run by Mohammad, where a boy who appeared to be 12 was allowed to beat some of the prisoners and shock them with Tasers.

In May, he said, they were moved again, this time to a base run by Ahrar al-Sham, where an elder took an interest in their plight. He ordered them to give written statements about their torture by the Nusra Front, and said their cases would be re-examined and that they might be released.

Instead they were transferred to cells in two other bases, also run by Mohammad and the Nusra jailers. In mid-July, the jailers removed the Moroccan and later a dentist they had detained, leaving the Americans alone.

This allowed a fresh opportunity to try to escape. Their cell was in a basement; the mesh and welding on one window was damaged and had been only partially repaired.

Schrier said he stood on his cellmate’s back and unraveled wires, opening a hole large enough to fit his head and one arm through. But he got stuck and had to return inside and rewire the mesh.

He and his cellmate argued over whether to try again. After a few days, he said, his cellmate agreed. Schrier opened a larger hole.

After the morning prayer, just before dawn, Schrier said, he pushed both arms out and followed with his head.

He passed through. He said he reached in, pulled his cellmate up. The man had a slightly heavier build than Schrier. He led with one arm, then his head, and stopped.

He was stuck. He slid back and tried leading with two hands. He was stuck again.

The street was silent, Schrier said. A light shone in their jailers’ first-floor office, directly above their cell.

His cellmate dropped back into the basement. Schrier said, “I’ll get help.”

His cellmate looked up, Schrier said, and told him, “All right, go.”