This book chronicles the spiritual journey undertaken by the young evangelical pastor of a small-town, American church when he embarks on a mission to help the members of troubled street gangs in New York City. Set in the late 1950's and early 1960's, the narrative traces the growth of his ministry from personal, one-on-one encounters into a thriving, sometimes miraculously funded, community outreach program. Along the way, the book explores themes relating to the power of Christian faith and the causes and effects of drug addiction.

The book begins with the author's description of the photograph (of a gang of teenagers accused of killing a polio-stricken fifteen year old) that eventually led him to change his life. He writes that through prayer, he came to believe that God's will for him was to travel from his small parish in rural Pennsylvania to the rough streets of New York City.

On his first trip into New York, the author discovers the depths of his innocence about the city, its justice system, and above all the nature of street gangs. His quest to visit the boys from the photograph is defeated at every turn; he feels humiliated and unsure about how to proceed. He is nevertheless reminded that "the Lord works in mysterious ways." After praying for further guidance, he decides to visit New York several more times, becoming more aware of how much work there is to do outside the particular gang he initially sought to help. A visit to his grandfather, a retired Pentecostal preacher, inspires him to consider broadening his mission to other members of other gangs. Again he prays and realizes he is being "called" to move to the city to begin his ministry there full time.

The author's first attempts at street corner evangelism result in the conversion to Christianity of a couple of the toughest gang leaders in the city - and the resentment of others. He also gathers allies, fellow ministers eager to help him free troubled young people from their addictions to drugs, sex and violence. At one point, the author initiates a series of rallies for the young people, which are at first sparsely attended and raucous, but through faith, prayer and trust, the author eventually wins the gangs over.

As the author's ministry expands and as he encounters increasing success with his techniques of reaching out to young people, the author again receives what he believes to be divine guidance. This time, he is inspired to fulfill his dream of establishing a drop-in center that the troubled youth of the area could use as a resource, a shelter from the horror of their lives. With the practical support of his wife and the financial support of some wealthy benefactors, he establishes what comes to be known as the Teen Challenge Center, and trains young students from Bible colleges across the country in the specific needs and circumstances of his ministry.

As the Center establishes itself and becomes more secure, it fosters and nurtures young people from the street as they awaken to a new, evangelically-based spirituality. Several of them, in fact (the author writes) move into the ministry. There are hardships (lack of funds, lack of food) but, the author writes, the Center's needs were all met through the power of prayer. Even though extended negotiations fail to win a full reprieve from the pending payment of a second mortgage, at the last minute (and exactly as prayed for) a donation for the full amount of the mortgage comes in from a wealthy donor. The Center, and the author, are free to continue their work. An epilogue describes how that work is expanding to other large cities with similarly troubled teen gang populations.