East Side Kids (1940)

"It's gang war on the streets of New York...when a bunch of half-pint racketeers go "civic-minded' to put the skids under a crime czar!"

After living all his childhood in the street, a young boy rapidly notices that crime doesn't pay, leading him to become a policeman. One day, one of his best friends goes to prison for a murder he didn't commit. The policeman tries his best to release the friend by proving his innocence.