The Green Lantern travels to the tiny Eastern European nation of Modora, to procure a stamp for his friend, Thomas Kalmaku. An old woman leads the Green Lantern to believe that Modora has no postal system. The Green Lantern uses his power ring to probe the thoughts of a more reliable individual, an elderly clockmaker. Ominously, the Green Lantern learns, from the clockmaker's thoughts, of a young inventor, named Bito Wladon. The clockmaker fears that Wladon is intent on carrying out terrorist acts, in the United States of America.
Wishing to put his tiny homeland on the map, Wladon intends to build a weapon of mass destruction, to be used against the United States of America, and the Union of Soviet Socialist Republics. Wladon has already made several advancements in harnessing sound as a weapon. The Green Lantern races back to the United States of America, to apprehend Wladon. By the time the Green Lantern reaches Coast City, Wladon has already begun his crime spree, stealing the components necessary to build his super-weapon.
The newspapers are calling Wladon, "Sonar". Learning of a robbery, in progress, at the Pontex Space Laboratory, the Green Lantern races to confront Sonar. The Green Lantern is rendered unconscious, by a concentrated burst of sonic energy. By the time the Green Lantern has regained consciousness, Sonar has escaped with the stolen isotopes. Despite the high profiles of Sonar's crimes, no mention is made of Modora in the newspapers. Wladon designs a new weapon, a tuning fork gun, to be used against the Green Lantern, in their inevitable next encounter.
The Green Lantern again confronts Sonar. The vibrations of the tuning fork gun disrupt the Green Lantern's brain waves, causing him to see the entire world in shades of yellow. Believing his power ring has been neutralized, the Green lantern helplessly watches, as Sonar gets away again. The Green Lantern uses his power ring to cleanse his mind of Sonar's illusion. The Green Lantern pursues Sonar, catching up to him over the Pacific Ocean. The Green Lantern uses his power ring to trap Sonar in a spout of water. The Green Lantern brings Sonar back to Modora, to answer for his crimes.
Sonar takes some consolation in the fact that his actions have raised Modora's profile in the world. In appreciation of his service, the Green Lantern is awarded Modora's only commemorative stamp, which the Green Lantern turns over to Kalmaku.
Hal Jordan, a test pilot for Ferris Aircraft, prepares for a reunion with his two brothers, Jack, and Jim. Expected to wear his old fraternity ring, Hal is distressed when it turns up missing. Hal's friend, Thomas Kalmaku, a mechanic for Ferris Aircraft, suggests Hal use his power ring to turn it into a replica of the fraternity ring. After meeting at Jack's home, outside Coast City, the Jordan brothers go hunting. Jim's girlfriend, Sue Williams, stops by the house, and lets herself in, to wait for Jim's return. Believing that Jim is the Green Lantern, Williams snoops around the house.
Williams finds what she believes to be the Green Lantern's power battery. After their hunting excursion, the Jordan brothers visit a local doctor to get treated for poison ivy. Hal, and Jim, are asked to remove their fraternity rings, so that their hands can be treated, Back at Jack's, the brothers go their separate ways, to rest up before the reunion party. JIm finds Williams waiting in his room. Williams confronts Jim with the "power battery", and accuses of him of being the Green Lantern. Jim denies the accusation, pointing out that the "power battery' is merely a lamp, from a vintage automobile.
Jim humors Williams by charging his fraternity ring at the lamp, while reciting the Green Lantern's oath. To Jim's surprise, upon demonstrating the power of the ring, he finds himself actually flying up towards the ceiling. Inadvertently, Jim renders himself unconscious, when he collides with the ceiling. Williams runs out to collect Jim's brothers. A pair of hoods break into Jack's house, steal the lamp, and abduct Jim. Hal spies their getaway car and pursues them, as the Green Lantern. It is at that moment when the Green Lantern realizes that he is wearing JIm's fraternity ring.
Hal, and Jim, accidentally swapped rings at the doctor's office. The Green Lantern borrows Jack's car, to pursue the crooks. Jim is brought before Mister Blackstreet, a criminal mastermind seeking stolen diamonds, hidden in the automobile's lamp. Blackstreet has actually re-assembled the vintage car, in his pursuit of the diamonds. Blackstreet demands that Jim turn over the diamonds. The Green Lantern storms Blackstreet's lair. Using his command over his own power ring, the Green Lantern makes it appear as if both his power ring, and JIm's fraternity ring, are generating energy constructs.
With the criminals subdued, the Green Lantern asks Jim to hand over his "fraternity ring" so that the Green Lantern can neutralize any lingering radiation. Blinding Jim momentarily with a flash from his ring, the Green Lantern switches the rings back, handing Jim the fraternity ring. After turning Blackstreet over to the authorities, the Green Lantern discovers the missing diamonds, in the base of the lamp. Jim continues to deny, to Williams, that his is the Green Lantern, to no avail