The American platoon stopped its Humvees in the road.

Ahead, a small boy of about 6, dressed in rags, staggered in circles.

Army Ranger Sean Parnell and his men were wary. It was July 2006 and they'd been in combat on the remote Afghan-Pakistan border for five months.

When the soldiers moved close enough, they saw that someone had gouged out the boy's eyes and burned the sockets black with a heated instrument. His teeth had also been knocked out.

"Jesus Christ, what is this?" said a hard-bitten sergeant.

In the nearby village, the unit's interpreter, Yusef, talked to an elder and learned what happened. The insurgents had swept through this village and punished the inhabitants for cooperating with the coalition.

They kidnapped the oldest grandson of the elder and took him to the mountains, where they gouged out his eyes and raped him for weeks.

The platoon medic did what he could for the boy and other brutalized children in this place the men came to call the "Village of the Damned." The elder thanked them and they drove on, even the toughest among them stunned by what they'd seen.

"There's not a day goes by that I don't think about it," said Lt. Parnell, 30, a Murrysville native. "All I know is that moment taught me that there is definite good and evil in this world. We don't always realize it in America, but the rest of the world can be a barbaric place."

The "Village of the Damned" is just one short chapter in Lt. Parnell's new book, "Outlaw Platoon," written with author John Bruning and set for release by William Morrow/HarperCollins on Tuesday. [See Facebook page here.]

Yet it captures the dichotomy of Afghanistan -- the contrast between Americans and terrorists, between good Afghans and bad, between quiet heroism and treachery.

Yusef, it turns out, is a spy. He later reveals to an Iranian cell of bomb-makers that the platoon plans to set up an observation post on a certain hilltop, allowing insurgents to seed it with mines. When the platoon arrives, villagers come out to watch. One of the mines explodes and kills Cpl. Jeremiah Cole.

But the elder whose grandson was tortured is the opposite. Gratified by American kindness, he later risks death to walk 40 miles through the mountains to warn of an impending attack.

"That's Afghanistan," said Lt. Parnell. "That incident is a microcosm of the whole country."

It's a world apart from Murrysville, where he grew up, and Cranberry, where he lives with his wife, Laurie, and two small children.

Lt. Parnell was attending Clarion University when he watched 9/11 unfold on television. Enraged, he joined the Army and found purpose, transforming from a listless college kid into a reed-tough Ranger with the 10th Mountain Division. He shipped off for Afghanistan in 2006 to take command of a 40-man platoon, nicknamed the Outlaws, with the goal of rooting out the Haqqani Network near the Pakistan border.

His book details his 16 months in combat, engaging Pakistan-based insurgents in numerous firefights in the mountains of Paktika Province. His men killed some 350 insurgents and lost just one of their own; two dozen were wounded.

The book differs from other memoirs coming out of Afghanistan in that Mr. Parnell includes an internal dialogue that reveals a sensitive leader. He's deeply affected by everything he endures, starting with his first day in Paktika when a little girl dies in his arms after a rocket blows off part of her leg.

"It was hard for me to see that," he says. "I felt like part of me was dying."

Early on, Lt. Parnell also expresses his fear of combat and questions his leadership ability.

"Sean's that kind of guy, he's very humble," said Sgt. Christopher Cowan, an Outlaw member who is now a police officer in Syracuse, N.Y. "But he was a very good leader who took care of his men."

Lt. Parnell overcomes his doubts in one harrowing moment, when his unit is pinned down by machine-gun fire and he must exit his Humvee to rally the men. He does, but even now he's not sure how.

"You can have all the training in the world, but you never know what it will be like until that first round cracks over your head," he said.

Staff Sgt. Phillip Baldwin, now training to be a lawyer in Illinois, remembers that day.

"Bullets are flying everywhere, people are shouting," he said. "It was nuts. And then Sean comes running by my truck and pounds on it. He was out there, and I had to get out and join him or he was going to get killed. As soon as I began to open the door, I can see bullets impacting, stitching their way to my door. I took a deep breath and jumped out. It was the hardest thing I've ever done."

Lt. Parnell evolves into a hardened commander over time, and the platoon becomes his family.

The narrative includes such characters as Master Sgt. Greg Greeson, the chain-smoking leader who stays calm under fire; Spc. Robert Pinholt, the radioman who reads John Steinbeck; and Abdul, a gentle Afghan interpreter who ends up killed by Yusef's machinations.

"The thing that made Sean's story so different is his level of insight," said Mr. Bruning, who embedded with U.S. forces in Afghanistan in 2010. "It's a combat memoir. But it's also a love story."

Yet that band of brothers bond only goes so far. Lt. Parnell calls out those who didn't measure up, such as the fellow leader who avoided the action, a sergeant who disappeared for weeks, another sergeant who froze in combat and the "mail bitch," a nasty female letter carrier. He debated how much of these elements to include but decided a sanitized version would serve no one.

"My agent said the best memoirs are always the most honest," he said.

Sgt. Cowan said the book is a truthful portrait of the platoon's experiences.

"You gotta be real," he said. "Combat is a horrible thing to go through. Some people crack. That doesn't mean they're a bad person."

Lt. Parnell also passes harsh judgment on the competence of the Afghan Border Police, the questionable fighting spirit of the Afghan National Army and the sincerity of the Pakistanis, since many attacks originated in Pakistan.

Outlaw Platoon constantly engaged the Pakistan-based Haqqani Network. Lt. Parnell thought the enemy would be a ragtag group of Taliban militia, which was the case early in the war. But the fighters had since retreated into Pakistan and regrouped. Now led by al Qaeda-recruited veterans, they were skilled.

"We'd never even heard of the Haqqani Network," Lt. Parnell said. "We didn't know what we were getting into. I was shocked by the enemy's ability to fight. They could do everything we could do."

Lt. Parnell struggled to retain his humanity in the face of enemies who carried 8-inch knives and would cut off his head if they got the chance. He'd seen it in videos. "I was terrified of that, to be honest," he said. "We always saved one bullet for ourselves."

The torture of the little boy from the Village of the Damned proved the nature of the enemy.

"That level of depravity is not something that is even on the American radar," said Mr. Bruning. "Yet that's something that the Taliban does."

Yet Lt. Parnell and his men showed restraint. In one engagement, a wounded insurgent tumbles down a slope next to his Humvee and stares up at him.

"His eyes never moved from mine," he writes. "I've never felt a more malign and sinister presence."

Spc. Chris Brown begs to be allowed to finish him off. The unit had lost Jeremiah Cole and is out for revenge. Lt. Parnell says no. He had studied the My Lai massacre in Vietnam and how the guilt had haunted the U.S. soldiers who participated. He says he wanted to spare Spc. Brown that fate.

"I loved Chris Brown too much to let him burden his conscience with this man's foul soul," he writes.

He spares Yusef, too. Early in the book, he catches him using a satellite phone but accepts his story that he was calling his family. He later learns that Yusef had arranged the death of Abdul, his rival interpreter. When Abdul's family had received threats from the Taliban, he left the U.S. base to check on them. Yusef alerted the insurgents, who ambushed Abdul.

"This is a mistake that I will have to live with for the rest of my life," said Lt. Parnell.

He writes of eating a meal with a joking Yusef, knowing that the Army was on to him but unable to reveal it. "I could kill you, Yusef," he says to himself. "I would pull that trigger and feel less remorse than if I'd just crushed a cockroach."

Yet in the end Yusef is arrested, not executed. "Our discipline and ability to choose the hard right in times like these are what make us the best army the world has ever known," Lt. Parnell writes. "And so Yusef lived."

Lt. Parnell came home scarred in 2007. He earned two Bronze Stars and the Purple Heart for a blast-induced concussion. He still has ringing in one ear.

He also suffers from post-traumatic stress disorder. The stigma of PTSD is not as bad as it once was, he says, but the macho culture of the military is still an impediment to treatment. He wants to change that.

He's studying for his doctorate in clinical psychology at Duquesne University and hopes to counsel others damaged by war.

"You have to go numb to survive," he said. "The problem is that a lot of vets stay numb when they come home. My goal is to help soldiers."

First Published: February 26, 2012, 10:00 a.m.