Sydney Westerfield has taken up her post as Governess, at Mount Morven House - a research establishment in Caithness where a vital secret experiment is underway. She is to tutor Kitty, the daughter of Herbert Linley and his wife Catherine, while they and Herbert's brother Professor Randal work on the Linley Process - a means of converting normal matter to the 'dark-matter' antigravity material that has taken humanity to the planets. But unknown to Sydney, the core of their machine is one of the cursed gems, whose history is so entangled in hers - and the hand of Valdavor Va - the Evil Genius Of Venus - is stretching out to grasp it!