With two armed guards by his side, Byron Mullens walks with several friends toward the inner perimeter fence, the two feet of barbed wire curls running along the top glistening in the sunlight.

They have already handed over their cell phones and keys, gone through a metal detector, signed in the log book and walked through a series of locked doors that won't open until the previous one is shut. Now Mullens and crew must go through another round of security, pausing as they get to the gate and holding up a badge.

"Mullens, zero-one-zero," he says, as another guard behind a thick-plate glass window takes a photo and notes his entry.

The 22-year-old Oklahoma City Thunder center walks a long, paved footpath toward the gym. That's when the comments begin.

"Hey, hey Byron!" one man calls out.

"Byron, what's up, man?" someone else yells.

"What's up, boy? You doing all right? You gonna come over here?" Mullens asks, motioning toward the gym.

Mullens spends most of his court time at Ross on the perimeter to work on his outside game. Courtesy of Ross Correctional Institution

"He's so tall, I bet he could dunk just by standing," says an elderly man, wearing his all-blues and walking with a cane. He grins; two of his front teeth are missing.

"Da-na-na! Da-na-na!" yells another, calling out the "SportsCenter" theme song. Mullens laughs and shakes his head.

The group walks through two more sets of fences and past several guardhouses before Mullens stands at the entrance to the gym.

His pickup game is about to begin. In prison.

Mullens was born in Canal Winchester, Ohio, and grew up playing basketball around Columbus. He lived off and on with his mother and five siblings until high school before moving into his own apartment, paying his expenses by working after school and on weekends as a plumber. During his junior and senior years of high school, Mullens lived with the family of one of his best friends. In his first year there, he and the friend visited a juvenile detention center to teach basketball clinics and talk to troubled teens about making better choices -- and also to play pickup games.

There wasn't any particular reason they played there instead of a nearby gym or court, Mullens said. He just "wanted to go and play basketball" and liked the "under-the-radar" level of competition.

After the Thunder's playoff run ended last May, Mullens began offseason workouts with a trainer and played pickup games at Ohio State University, where he played for one season before going pro in 2009. But after talking this spring with friend Jeff Lisath, the assistant warden at Ross Correctional Institution in Chillicothe, Ohio, Mullens decided to play inside prison walls once again.

"I played ball at some places for juvenile kids when I was in high school and I kinda wanted to get back into it," Mullens said.

By mid-July, he played in his first pickup game at Ross, which houses mostly level 2 and 3 prisoners -- medium and "close" security, respectively. (The scale ranges from 1 to 5, with 1 representing "minimum security" and 5 symbolizing "administrative maximum.")

"They play some really good basketball up here," Mullens said.

“ It gives you something to look forward to. A lot of these guys aren't going home, so when they get the opportunity to play someone of that skill set, it makes their day. ” -- Ryan Janes, a Ross Correctional Institution inmate and one of its top guards

The walls of the dimly lit gym here at Ross are a pale yellow and lined with painted jerseys bearing the names and numbers of numerous famous basketball players. Head warden Tim Buchanan says they plan to add a "Mullens 23" jersey to the collection. There are no team benches; players either sit on the bottom row of the wooden bleachers for spectators or in chairs courtside. No towels, no water boys. Just a small yellow cooler with plastic cups.

When he stepped onto the court for that first game in July, Mullens heard close to 300 inmates yelling and jeering from the bleachers. Word had spread about Mullens' visit -- a showcase the inmates didn't want to miss. Most of the 2,270 inmates at Ross are from Ohio and, like 31-year-old Ryan Janes, major Buckeyes fans. While they're occasionally allowed to watch NBA and college basketball games on TV in the central viewing room, most had not seen an NBA player up close.

Mullens' team won his inaugural game in overtime. The inmates have yet to win a matchup against Mullens, but Janes, a 5-foot-10 Chillicothe native who was incarcerated in August 2006 for what he would only describe as "a mistake after I got involved with the wrong people," predicts it will happen.

One of the prison's best point guards, Janes was a teammate of Mullens in the inaugural game. But he was really looking forward to his first game against the NBA center.

"I was excited and nervous because I wanted to see where I was at as far as skill level," Janes said. "I wanted to rough him up, but not hurt him."

The games are physical, but Mullens agrees that no one is trying to injure him. The institution has an "A" league for the more talented players, a "B" league for the less talented players and a 40-and-over league. Only "A" league, level-2 players are selected for the game when Mullens visits.

"The guys are on their better behavior when Byron is here because they know everyone's watching," said Justin Patrick, a former Shawnee State basketball player and the prison's recreation director. "I don't pick the dirty guys to play against him, just the good-character guys."

Mullens has yet to sustain any injuries -- except perhaps to his pride.

Inmates trash talk and yell at him on every possession to "dunk the ball," and the taunts only increase when Mullens steps behind the arc. But Mullens says he's not there to dominate the boards. Instead, he sees these pickup games as an opportunity to work on his outside shooting and ballhandling. Since the tallest inmate Mullens has faced is 6-8 and most hover around 6-foot, the majority of his shots are uncontested. The inmates try to counter with speed and 3-point shooting.

Mullens stands inside Ross' gym with warden Tim Buchanan and assistant warden Jeff Lisath. Courtesy of Ross Correctional Institution

Like most pickup ball, defense is not the focus of these games, which consist of three 20-minute periods. And even though inmates who have taken referee tests are paid 75 cents per game to serve as officials, fouls, traveling and three-second calls are hard to come by.

"The refs aren't very good," Janes said. "You'll get the calls you get."

But what the game doesn't lack is good competition.

"Honestly, what surprised me most coming in here was how good these guys are," Mullens said.

While most inmates in the games have never played competitive basketball beyond high school, they often shoot around, play pickup or lift weights several hours a day. As Mullens points out, there's a lot of time to spend improving their games.

Twan Whitehead, a 30-year-old Columbus native who entered Ross Correctional in June of 2008 following a robbery conviction, felt Mullens initially held back his intensity. But now Whitehead says, "We don't take it easy on him and he don't take it easy on us."

Mullens and his crew don't linger very long after the games, but he makes a point to talk to the guys when he has time. He's recognized around the prison and his visits are still highly anticipated.

"It gives you something to look forward to," Janes said. "A lot of these guys aren't going home, so when they get the opportunity to play someone of that skill set, it makes their day."

After signing a one-year contract with Greek team Panionios in early September and playing abroad for a few weeks, Mullens is back in the United States to work out with a personal trainer and his Thunder teammates.

Both Janes and Whitehead said they'd love for Mullens to bring Kevin Durant, Russell Westbrook or any of his Oklahoma City teammates to a pickup game at Ross. For now, though, they're grateful to have an NBA player on the court.

"I know people have their own opinion that if they're in prison, they shouldn't really get that freedom," Mullens said. "But they're doing the time for what they did, so the way I see it, just coming in here and playing basketball with them I could be anywhere else but I'll be in here playing. Basketball is basketball."

Anna Katherine Clemmons is a reporter for ESPN The Magazine and ESPN.com.