"It got to the point where there was no respect for any life, not even yours."
Beah was eventually rescued by UNICEF and spent eight months in a rehabilitation facility for child soldiers. His is an extraordinary and horrible story, and one that he stands by in the face of his doubters.
"I recall everything that happened during the war, including dates. One of the things I did as a child was every year, every four years, watching soccer, the World Cup. I don't recall watching the World Cup of 1994. If it had been peaceful, I would have watched."
Beah writes in his book that he has a photographic memory. And what of his critics?
"The people are simply misinformed or they have a purpose which is not to help in this particular matter in terms of the children. They simply cannot believe that this is possible for someone to come out of this and do something."
He has certainly done something. Beah graduated from Oberlin College in the United States, has written his book and now has a foundation that is helping to build a school in Sierra Leone.
"What changed my life significantly was having an education," he said. "Most of my life I've lost everything that was dear to me. When I graduated college I realized this was one thing that no one can take from me."
Going back to Sierra Leone has been important, he says, as has sharing his story of not just what it was to go to war, but what it has been to come back from it. Despite everything that happened to him, he says he believes people are fundamentally good.
"I won't lie to you, it took many years to get myself to go there. But I'm happy that I did it. It strengthened my belief in the possibilities of things changing more and more. Because I'm standing in places where, not long ago it was charred, gunfire houses burned, and now there's life there."