After World War I, Armistice Lloyd Hart goes back to practice law, former saloon keeper George Hally turns to bootlegging, and out-of-work Eddie Bartlett becomes a cab driver. Eddie builds a fleet of cabs through delivery of bootleg liquor and hires Lloyd as his lawyer. George becomes Eddie's partner and the rackets flourish until love and rivalry interfere.
Having once again avoided criminal conviction, Professor Moriarity develops a murderous plan to “finish off” his last major nemesis, Sherlock Holmes, by making him fail to prevent the perfect crime. Does it involve a family curse, the crown jewels of England, or something else…
A corrupt D.A. with governatorial ambitions is annoyed by an investigative reporter's criticism of his criminal activities and decides to frame the reporter for manslaughter in order to silence him.
Dr. Henryk Savaard is a scientist working on experiments to restore life to the dead. When he is unjustly hanged for murder, he is brought back to life by his trusted assistant. Re-animated he turns decidedly nasty and sets about murdering the jury that convicted him.
Detective Guy Johnson's client, Willie Heywood, is framed for murder. While Guy hides him so he can catch the real killer, both of them are nabbed by the police, tried, convicted and sentenced to jail: Guy for a year with Willie to be executed. On the way to jail, Guy comes across a clue and escapes from the police.
When a confused eyewitness identifies New York City cabbie Brick Tennant as a killer, he is sentenced to death for a murder that he wasn't involved in. Though no one is willing to listen to the innocent prisoner's pleas for freedom, Brick's faithful fiancée, Mary, knows that her lover is innocent because she was with him when the crime was committed. As the scheduled execution draws ever nearer, Mary begins to investigate the murder herself.
Johnnie learns crime from petty thug Frank Wilson. When Wilson kills a pawnbroker with a gun stolen from Johnnie's sister Madge's fiance Fred Burke, Fred goes to Sing Sing's death house. Wilson uses all the pressure can to keep Johnnie silent, even after he and Johnnie themselves wind up in the big house.
Suave private detective Simon "The Saint" Templar arrives in San Francisco and meets Val, a woman whose police inspector father killed himself after being accused of corruption and dismissed from the force. Convinced of the man's innocence, Templar takes it upon himself to vindicate the memory of Val's father. To do so he must take on the city's most dangerous criminal gang, while also battling hostile members of the police department.
When the murdered body discovered by beautiful, vivacious socialite Melsa Manton disappears, police and press label her a prankster until she proves them wrong.
A chemical manufacturer is killed just after asking detective James Wong to help him. So detective Wong decides to investigate this as well as two subsequent murders.
A wealthy society doctor decides to research the medical aspects of criminal behaviour by becoming one himself. He joins a gang of thieves and proceeds to wrest leadership of the gang away from it's extremely resentful leader.
Mobster "Baby Face" Martin returns home to visit the New York neighborhood where he grew up, dropping in on his mother, who rejects him because of his gangster lifestyle, and his old girlfriend, Francey, now a syphilitic prostitute. Martin also crosses paths with Dave, a childhood friend struggling to make it as an architect, and the Dead End Kids, a gang of young boys roaming the streets of the city's East Side slums.
When a hard-working machinist loses a promotion to a Polish-born worker, he is seduced into joining the secretive Black Legion, which intimidates foreigners through violence.