Two scientists, one a woman, the other a man, simultaneously discover a life-extension technology. Fearing it would be misused by the rich and powerful, they separately set about using or withholding the elixir of life according to their own motivations.

Wyndham struggled with this story and he was unhappy with the ending. The ideas explored are prescient, conceived long before the disturbing aspirations of today's billionaire trans-humanists.

Without the fight for survival and action-packed thrills of his other novels, this one is a more contemplative read. Not his best, but still excellent.