Britt Reid, newspaper publisher, is waging war against the racketeers. Masked as the Green Hornet he hunts the biggest of all game-public enemies that even the G-men cannot reach. With his faithful valet, Kato, he visits a tunnel being constructed under the river with faulty material and equipment. Forcing the foreman into an air lock, with an ingenious gas-gun he is ordering him to name the higher-ups in the construction racket, when an air compressor fails, and water comes rushing in! Will our heroes escape in time?

Our hero Britt Reid learns that the men killed in the tunnel disaster were insured in the construction company's favor, through a broken named Mortenson. Masked as the Green Hornet, Reid locates Mortenson, but before he can force him to confess, Axford and the police arrive and the Hornet has to flee. Monroe, acting boss of the rackets, orders Mortenson to destroy all papers and leave the country. The Hornet and Kato pursue Mortenson, who boards a train. The Hornet leaps aboard after him. Will our hero be able to stop the evil Mortenson before he can leave the country?

The newspaper publisher Britt Reid suspects the Bartlett Flying School of a scheme to collect insurance on both planes and student flyers. As the Green Hornet, Reid visits the flying school, binds Bartlett, head of the school, then forces Bartlett to fly with him in a plane “specially serviced” for a student flyer. Bartlett, facing death, confesses the plane has been fixed to burn in mid-air, and pleads with the Hornet to remove his bonds so he can bail out. Once free, Bartlett treacherously attacks the Hornet. Will the Hornet be able to fight off his attacker?

Our hero Britt Reid, determined to smash the stolen car racket, allows his car to be taken form a parking lot he suspects, then trails it to the Meadows Garage where it mysteriously vanishes. Reid recognizes one of the garage mechanics as Pete, a racketeer formerly with the flying school; and that night, as the Green Hornet, he visits the garage to question Pete. Pete, alarmed at the sight of the Hornet makes a dash to escape. In his "Black Beauty" driven by Kato, the Hornet pursues Pete’s car. Will he be able to overtake Pete and get the information he needs?

Britt Reid trails the theft of his car to the Meadows Garage. Axford follows one of the Meadows' mechanics to a junkyard, where he and Reid narrowly escape death when the racketeers discover who they are. Meadows, realizing Reid is hot on the trail of his stolen car orders it destroyed with a time bomb. Before the bomb explodes, the Green Hornet confronts Meadows and terrifies him into a confession. The racketeers discover and attack the hornet. Kato helps the Hornet knock out Meadows and overcome the racketeers. Can they escape with Meadows before more trouble comes their way?

The newspaper publisher Britt Reid, investigating sabotage of Whippet Line buses, suspects that Rockford, head of the Blue Streak, a rival bus line, belongs to the crime ring responsible. Avxord conducting an investigation of his own, visits the Blue Streak headquarters and is trapped and made prisoner by the racketeers. Reid learns of Axford’s predicament and, disguised as the Green Hornet, succeeds in freeing Axford and forcing a confession from Rockford. But Rockford’s henchmen return, a fight ensues, and The Hornet is outnumbered. Will the Hornet be able to escape with his life?

Britt Reid, disguised as the Green hornet, captures Sligby, the murderer of Charles Roberts, then trails the trucking racketeers and surprises two of them about the destroy a trainload of perishables. The Racketeers attempt to escape in a truck, the Green Hornet boards the truck and battles one of the men, while the other races the truck toward a bridge to get help from two of his pals. But his pals, to prevent a rival truck crossing the bridge to make deliveries, have weakened the bridge supports. Will the Green Hornet be able to win his battle and save both of the trucks that are speeding towards certain doom?

Our hero Britt Reid, disguised as the Green Hornet, is snapped by a Sentinel photographer as he hurriedly leaves the house of a cleaner named Lavensen. Monroe sees the pictures in the Sentinel and, realizing the Hornet is on the trail of Lynch, head of the Cleaners' racket, orders Lynch and his shop removed and evidence planted pointing to the Hornet as the perpetrator of the crime. Corey and Dean saturate Lynch’s plant with combustible cleaning fluid, and when the Hornet traps Lynch in his shop, the shops begins to light fire. Will the Hornet be able to escape a fiery death?

Britt Reid, Axford and Jenks go to the Martinson place on an anonymous tip that it is the hideout of The Green Hornet. Outside the house, Reid makes an excuse to leave Jenks and Axford. Donning The Hornet garb, brought by Kato, he enters the house, surprising three gunmen ambushed there. A fight follows, and the gangsters escape as Jenks and Axford rush in. Cornered by his own friends, The Hornet hides in a closet. But Axford has seen him enter, and rushes to the door with a drawn gun. Will the Green Hornet be able to escape this trap? Will Britt Reid’s secret identity finally be revealed?

Our hero, Britt Reid, battling the crime ring in a mayoralty election, secures evidence that ballot boxes have been "stuffed." The ring candidate is elected and The Sentinel demands a court order for a recount. Monroe hurries his henchmen to seize and destroy the ballots, but The Green Hornet gets possession of the ballots and starts with them in an armored car to a safe hiding place, pending the courts' order. Monroe learns of the route taken by the armored car, and sets a trap for our hero on a dangerous mountain curve. Will the Green Hornet be able to survive the deadly trap? Will he get the ballots to the courts in time?

The Green Hornet, or his true identity, Britt Reid, is investigating sabotage directed against the shipping business of young John Roberts. The Hornet causes the arrest of Max Gregory, an illicit munitions dealer. The Racketeers strikes back by attacking a trainload shipment being made by young Roberts. Reid, masked as The Green Hornet, with Kato driving the "black beauty" pursues the train, boards it at full speed, and attacks the gangsters. But during the fight, Roberts' cars, uncoupled by the gangsters roll back down the mountainside. Will the Hornet be able to switch the track in time? Will Roberts’ cars be destroyed?

In this exciting conclusion, Britt Reid sends Axford and Jenks to spot gangsters among the carnival crowd at the Cooper Zoo who are forcing "protection money" from Cooper by threatening sabotage. The Green Hornet then goes to Cooper's office, where he traps Lefty Bates, strong-arm man of the crime ring, and forces his to write a confession. Axford and Jenks, battling gangsters outside, overturn a popcorn stand which starts a fire. People and animals run amuch and stampeding elephants wreck the building, in one of which the Hornet is questioning Bates. Will our masked hero escape with his life? Will Bates' confession be finished before the impending doom of the crazed elephants?