Answer: It bulked up, bought a loincloth and set off into the wilderness to seek the Book of Knowledge.
Cord (Jeff Cooper) is a wandering weirdo. At the opening of the film he is participating in a fighting contest supervised by Roddy McDowell. You could repeat this scenario today and call it Ultimate Wizard Fighting.
Anyhoo, Cord cheats, sort of, and Roddy gets to utter the immortal words: "Morthond wins." He says this with all the enthusiasm of a fat guy on a diet reaching for another rice cake. So Morthond, who looks like he should be in a low rider in Albuquerque, not roaming the barrens with a sword, sets off to find Zetan, a sort of Scientologist who guards the Book of Knowledge.
And Cord, like the big ol' lovable puppy dog he is, just follows along after him, so when Morthond runs into the Monkey Man and is mortally wounded Cord's available to help him commit hari-kiri.
That's what friends are for.
Moving in and out of all this stunning mise en scene is The Blind Man (David Carradine) who can kung fu an entire gang of thugs without a whole lot of trouble. He also plays the flute. Cord decides Blind Guy shall be his teacher, and he annoys Blind Guy with his constant yakking.
So Cord has to go through all these trials - the Monkey Man, Chang-Sha and what the credits list as "Death" but what really looks like David Carradine dressed as a cat. He has sex with Chang-Sha's ninth wife, who gets crucified for her trouble, and comes across Eli Wallach, submerged in a big vat of oil in the desert. (The exchange between Cord and the Man in the Oil is worth the NetFlix fee.)
Finally Cord gets to the island, meets Zetan (Christopher Lee) and the gang, and finds the Book of Knowledge, which is not what he expected.
Summary: Automatic one coil deduction for no nudity. David Carradine, made up as a monkey, in a loincloth. Roddy McDowell, dressed in a bathrobe and a pointy white hat, saying "Morthond wins." Extras from "Planet of the Apes" to make Roddy feel at home. Kabuki belly dancers and the world's worst rhythm section, courtesy of Chang-Sha, desert chieftan (also played by Carradine). Crucifixion of pretty wife. Unpleasant thought about what the fellows on the Island of Peace do for fun, besides tend the roses. Eli Wallach indulging in the world's most extreme Temptation Removal Procedure (TRP). Gratuitous wooden flute music that doesn't match the soundtrack.
Circle of Iron, with its ponderous pseudo-Zen platitudes and mock-heroic structure should be just another lame sword 'n' sorcery epic, designed for the eighth grade market. It's just good enough to escape that fate and earn three-coil status in the CACA pantheon.
At 102 minutes it's also short, which helps.