Brad Hardy had a series of adventures in the Kingdoms of the Underworld.
Kingdom of the Snake Men
Brad Hardy and his partner Lorraine Lewis were stranded in the desert mountains of Mongolia, where they encountered a race of Snake Men with a human prisoner. Brad and Lorraine defeated the Snake Men and rescued the prisoner, who turned out to be Prince Kardos of the Underground Kingdom of Agharti.
Kingdom of the Dre
Brad, Lorraine and their new ally, Prince Kardos, entered the Kingdoms of the Underworld with the intention of reaching the prince's homeland, but along the way, the trio were captured by a race of Rat Men and their human leader, King Naga of the Dre. Brad and Kardos were forced by Naga to fight the Black Magician of the Dre, but they were able to defeat him and escaped along with Lorraine from Naga's clutches.
Brad and his companions then encountered a race of Ape Men, who attacked them along with their Ape God. Brad was able to defeat the Ape God, but while on the run from the Ape Men, they encountered yet another threat, a giant spider. Lorraine was kidnapped by the Grey Men while Brad and Kardos were distracted fighting the spider.
Kingdom of the Grey Men
Brad and Kardos were brought to the City of the Grey Men by an expelled High Priestess, but were quickly taken prisoners by General Porgo and King Marius. Brad led a prisoner revolt and successfully defeated the general's forces, but having suffered heavy casualties, he was unable to continue the attack on King Marius to free Lorraine.
Still intending to rescue Lorraine, Brad and Kardos traveled through the Gray Forest to reach Marius' palace, but their journey took a detour when they entered the Grey Lake and the strong currents carried them to the Underwater Kingdom of Merlania. There, Queen Claudia forced Brad to fight Lord Zion, the strongest man in Melrania, to earn the honour of becoming King, a prize that Brad was not even interested in the first place.
Brad defeated Zion and reluctantly became King of Merlania, but he and Kardos took advantage of a hunting expedition to escape the underwater kingdom. Having finally reached the palace, Brad once again encountered and fought General Porgo.  The outcome of this battle, and whether Brad and Kardos were able to rescue Lorraine, is unknown.
Powers and Abilities
- Hand-to-Hand Combat (Advanced): Brad Hardy was able to defeat magic users, low-level gods, and super strong opponents, using only his fighting skills.
- Leadership: Brad Hardy successfully led some prisoners to defeat an organized army.
- This version of Brad Hardy, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- The 28-episode career of Brad Hardy was marked by several changes from one writer/artist to another, starting at New Fun Comics #3 with Richard Loederer, changing at New Fun Comics #6 to W.C. Brigham, then again at More Fun Comics #9 to A. Leslie Ross, and again at More Fun Comics #12 to Tom Hickey, who stayed with the feature until its final episode, in More Fun Comics #31. At that point, the series ended abruptly, in mid-cliffhanger.
- Brad's adventures, involving Snake Men and an underground kingdom called Agharti underneath Mongolia, seem to be inspired by the 1922 book Beasts, Men and Gods by Polish author Ferdynand Ossendowski.
- 30 Appearances of Brad Hardy (Earth-Two)
- 2 Images featuring Brad Hardy (Earth-Two)
- 2 Quotations by or about Brad Hardy (Earth-Two)
- Character Gallery: Brad Hardy (Earth-Two)