 Recent college graduate Jay Shaw masters a switchblade, adopts the pseudonym Phil Beldone and moves to a notorious Brooklyn neighborhood to infiltrate a gang, the Barons, so that he can write a book about juvenile delinquents. The Barons require that he complete a three-step initiation. First he must run a gauntlet of their members; secondly he must win the heart of a "deb," a female gang affiliate; and finally he must murder a chosen victim. He runs the gauntlet unscathed and romances Feline (Lynn Loring), but when the gang plans to roll and kill a fleabag derelict, Phil intervenes to save the old man, then convinces gang-leader Tiger that he should usurp Candle s war commander position, angering Candle. Candle and Fish break into Jay s hotel room and steal his bankroll, along with his notebook about the gang. When Tiger reads the notebook to the gang, they label Phil a rat and stool pigeon. He is set up to take the rap for a gang crime, but Feline bails him out. Just outside the jail, he meets Feline, but Candle and Fish ambush them, telling him that it was Phil s bankroll that they gave to Feline for the bail money. They try to knife Phil, but Feline defends him, taking a fatal stab. Police cars swarm into the area, apprehending everyone.