In 2076 AD, Earth has been conquered and humanity brutally enslaved under the cruel tyranny of the Kalkar invaders whose evil was spawned from Va-nah, the Moon's hollow interior. Julian 7th, descendant of the great hero who led the first expedition to Va-nah and nearly defeated the Kalkars-receives a mysterious transmission from the planet Barsoom. The desperate plea from the Red Planet swiftly hurls Julian upon a lonely quest into the heart of Va-nah where he teams up with an U-ga princess and a fierce alien quadruped, and launches a daring rescue to save a lost Barsoomian ambassadorial mission. The success of this mission depends on an unlikely alliance with the Warlord of Mars to assail the enemy's impregnable stronghold. If Julian fails in this quest, humanity-and the entire solar system-will never escape the iron grip of the Moon Men.