Holly Williams Reports from Syria on Tonight's CBS EVENING NEWS

CBS News Correspondent Holly Williams reports from inside Syria, where she speaks with a teenager who says he was forced to fight alongside ISIS. The report will be broadcast tonight, Oct. 21 on the CBS EVENING NEWS WITH SCOTT PELLEY (6:30-7:00 PM, ET) on the CBS Television Network.

Williams spoke with 15-year-old Kareem Mufleh in the basement of a prison in northern Syria, where men accused of being ISIS terrorists are being held by a Kurdish group fighting against the Islamic extremists.

"They captured my village and gave me a choice-either join ISIS or be beheaded," Mufleh told Williams in Arabic.

In its brutal attempt to establish an Islamic state, ISIS has embarked on a reign of fear by carrying out mass shootings and public executions. Mufleh told Williams he was a witness to massacres when ISIS seized villages in Syria and claims that ISIS gave him an anti-anxiety drug, Zolam, before going into battle.

"That drug makes you lose your mind," he said. "If they give you a suicide belt and tell you to blow yourself up, you'll do it."

Williams also spoke with two other prisoners inside the Kurdish jail, both local Sunni men accused of supporting ISIS. The men were led into the room blindfolded, terrified and insisted they are innocent.

Steve Capus is the Executive Producer of the CBS EVENING NEWS WITH SCOTT PELLEY and Executive Editor of CBS News.