For countless years the enigmatic city of Klagan had rested beneath the racing moons of ancient Mars. Forbidden, guarded, sheltered in the cup of the Blue Mountains and surrounded by waterless desert. It rested there, a place of a thousand rumours and whispered fantasies, and gave birth to muttered tales of incredible wealth and riches. To this city came Halmar, the guide; Lorna, the dancer from Venus; and the man called Smith. Defying the ban of the Terran Authorities, the fanatical Drylanders, and the harsh desert, they reached the crystal walls of the strange city. There they found a tremendous mystery, the deserted artefacts of a vanquished civilisation - and found themselves snared in an incredible trap. For Klagan was more than a city. It was. . . What it was and how the intrepid adventurers solved the incredible secret of the mysterious city makes this an exciting tale of science and plausible speculation, action and human motivations.