Wealthy publisher Britt Reid and his trusted servant disguise themselves as vigilantes, The Green Hornet and Kato as they battle ruthless crime lord Crogan and his varied rackets across the city. Sequel to The Green Hornet serial.
At a deserted river house, the Hornet and Kato break up a meeting between the crime syndicate and foreign agents. The racketeers flee. In hot pursuit, the Hornet dangerously boards the crooks' car just as it careens up the ramp of an open drawbridge to plunge headlong into the swirling waters.
Seeking to foil the plot to substitute a clever actress for heiress Frances Grayson, The Green Hornet learns of the hideout of the kidnappers. The Hornet takes Miss Grayson to an unoccupied lodge. Waterson, a racketeer chief, finds them just as lightning strikes the building, blotting it out in a sheet of flame.
When the Hornet arrives at the dam, he halts the attempt to close the flood gates at the power plant and blow up the turbines. He then threatens to light the explosive fuses himself if his prisoners will not tell him who their leader is. When other henchmen arrive, a battle ensues and the Hornet is thrown against a large control board of switches. There is a flash of electricity.
Realizing the Hornet will soon know the whereabouts of the secret ammunition warehouse, Crogan, mastermind of the racketeers, orders one of his bombers to drop a load of explosives on the building. Just as the Hornet arrives, the bomb hits and the warehouse is destroyed in a deafening blast.
Adapted from the radio broadcast of May 26, 1938. At a steel plant, a vat of molten metal is overturned near the Hornet. At night he returns to inspect the secret laboratory where a powerful anti-aircraft bomb is being prepared for a foreign agent. When the Hornet tries to force the scientist in charge to reveal the identity of the master criminal, the man blows up the lab.
