This is a factual account of the way the police work in a large city from the minute a call comes through to the writing of the final report in the 124 room at the 21st Precinct. Frank Kenelly is Captain in command of the 21st. A police patrol man has been injured while chasing boys out of a condemned tenement building. Captain Kenelly as commanding officer is obliged to make a detailed investigation to determine if the injury was in the line of duty. 

A boy hitched a ride on the back of a truck and fell off right under the wheels of a car. The boy was a member of the Red Tiger club.