Tara of Helium, daughter of The Warlord of Mars, is lost during a freak storm, her Flyer blown off course and damaged. When the storm abates, Tara finds herself in the weird and unnatural land of Bantoom, home to the Kaldanes, a race of brains with-out bodies. The only man able to rescue her is Gahan, Jed of far off Gatho, the one man Tara of Helium wishes never to see. No sooner do they escape from the Kaldanes than they are captured by the Chessmen of Mars, a hidden people in a far off city that is obsessed with an earth-like chess game called Jetan.. There is a catch to the rules, however, that may spell the doom of them both....