Leigh Brackett was a pulp writer and hollywood scriptwriter both, and Sword of Rhiannon (an expanded version of Sea Kings of Mars) is one of her all too rare novels. Matthew Carse is an Indiana Jones type archeologist on Mars - a Mars of aging, decadent civilisation slowly drowning in dust - who is thrown back in time when he tries to rob one ancient grave too many. The opening vision of the new world he finds himself in is beautifully juxtaposed with the same scene on "modern" Mars: what are "now" old stone quays jutting into dust far away from the low-canals are vibrant and alive to a pounding Martian white surf.
From there a rousing tale follows - a mixture of magic and technology, of winged men and fearsome monsters, and a femme who is most definitely fatale. This is old-time planetary romance, with swords and beam weapons and slave-driven galleys coursing across a glittering sea. In the background is Rhiannon, a being (god?) of fearsome power who has a definate interest in Carse. Whether Rhiannon is friend or foe is unclear - and actually, who are friends and foes in this distant past is always murky.
This is Brackett, so there is keen dialogue with a witty sidekick, stunning cinematic scenery, and a gritty edge to everything. Its easy to see how this could be adapted to the big screen, and to an extent I am surprised no one tried.