This is EVAN HUNTER whose powerful and controversial first novel, THE BLACKBOARD JUNGLE, was a book, magazine and motion-picture sensation last year. Despite his youth (29), he has sold many short stories, a play, seven mysteries and several novels. Here are a group of his short stories concerning youngsters and crime. Stories of teen-age gangs, of girls in trouble, of Russian Roulette. The ordeal of a dope addict, the sex murder of a baby sitter, the menace of a mugger. Here are the stories behind the headlines — tragic, frightening, accurate episodes of life in the modern jungle, the streets and cellars, the hallways and roof tops, the parks and slums of a big city