Ernie Brenner and his partner Detective Frank attempt to put a crook behind bars who sells guns to juvenile delinquents. Frank becomes frustrated in his efforts to convict the gangster and starts to cut corners to get the evidence he needs to make the arrest stick.
Ernie is rattled after a shooting a disturbed young man who stabbed him and then attacked another police officer. The doctor treating his wounds doesn't give him much sympathy, but he meets a pretty nurse who is genuinely concerned and she accepts his offer of a dinner date. Meanwhile Roy organizes a dragnet to capture a knife-wielding mugger in Central Park.
Ernie Brenner goes undercover to investigate parents' complaints that their children are spending their lunch money on a pinball game in the local candy shop and discover that the old couple who run the store are running a small-time gambling operation.
Roy Brenner and his men pursue a burglar but lose their quarry when the man swings up to the roof like a seasoned athlete. Suspicion falls onto an acrobat friend of Ernie's, but the young detective stands by his friend even as the evidence piles up against him.