After reporter Pat Allen is killed at the Daily Sentinel by a leopard, Britt Reid finds a transmitter in a cigarette box. Later, D.A. Scanlon informs Britt of the discovery of a perfect diamond on Allen's desk. Digging around, Reid discovers that the gemologist had been working on producing synthetic diamonds.

Part two picks up with a GREEN HORNET visit and proposition for Peter Eden, owner of the Vale of Eden. After Peter uses Vanessa Vane to double-cross the Hornet, the Hornet re-visits Peter and uses his own dream machine on Peter to foil the last crime for the evening.

Organized crime's ""Protection"" Boss Duke Slate decides it's time to acquire the oriental businesses in town and uses Low Sing's gang to handle his influence. Low Sing, a martial arts professional, instructs his craft to his gang using the actions of a caged Preying Mantis, analogizing its intricate moves to proper Kung-Fu application. After a kidnapping, engineered by Low Sing, a challenge between Low Sing & Kato results in an interesting result.

After a rash of wealthy homes are burglarized, Reporter Mike Axford becomes so suspicious he places himself at the next possible home to be targeted, only to find himself being arrested, behind bars, for suspicion of murder.

""The Sally Bell"" a cargo ship with $2 million in narcotics en route to the U.S. from Hong Kong, is initially lost with her crew at sea, now mysteriously shows up at a salvage yard. The only survivor, Gus Wander, knows ""The Secret"" of her special cargo with only one big problem -- he's currently unconscious.

Its election time again and District Attorney Scanlon is running although someone wants to permanently remove him from the ballot.

An arsonist wreaks havoc setting fire to buildings at the stroke of midnight. The Green Hornet and the District Attorney work behind the scenes to aid the Commissioner to put a stop to this HOT situation. Throughout the arsonist's reign, Reporter Mike is kidnapped.