Carter packages Tower's science fiction elements with pulp-vivid aplomb. Its action-packed plot involves a master thief (Kirin), who is hired by the rich, portly Doctor Temujin to steal a legendary jewel -- the well-guarded Heart of Kom Yazoth, a demon associated with widespread destruction. Kirin and Temujin are en route to enact the dangerous theft, when they are taken prisoner by Azeera the Witch Queen, who also wants the jewel, with which she will rule the known universe.
Other characters in this fast-paced, exciting mix include: Caola, an Amazonian War Maid of Nar, whose wits and physical prowess may prove valuable to Kirin and Temujin; evil wizards of varying power, Pangoy the Nexian and his magickal master (Zarlak), who also commands the vicious Death Dwarves, whose job it is to guard the Iron Tower, where the jewel -- also called the Medusa -- lies beyond a series of elaborate traps.
There is not much in this story that will surprise readers familiar with science fiction-pulp tropes, but Carter's well-sketched characters, lean-and-mean storytelling and cinematic-friendly writing keeps Tower fun and thrilling: worth owning, this.
Tower of the Medusa was packaged as a reverse-bound "Ace Double" novel, which means that if readers flip the book upside down and over, there was another science fiction novel, penned by another author, on the other side. (Considering that these books sold for 75 cents a pop, this seems like a great deal, even back in the Sixties.)
In this case, the flipside novel is George H. Smith's Kar Kaballa.