If this novel had stopped about two thirds of the way through, it would have got the highest possible rating from me. It starts with two genetically-engineered 'rescuers' (one a human-looking woman, Ariadne, the other, Angelo, who resembles a giant apeman and has a claw instead of one hand) journeying to find Pioneer Murray. The Pioneers were humans sent out on one-way journeys to unexplored planets, with equipment to build a habitat if needed and to investigate their planet. All space travel is sublight, using 'deep sleep', so centuries have passed on Earth. After the Pioneer programme ended, Earth has nearly destroyed its biosphere and humanity is becoming sterile. Retrieving the Pioneers is vital to rejuvenating a dying Earth. Yet 'rescuers' are hated by those left on Earth and although some Pioneers have been found and returned, none have proven the key to rejuvenating humanity.

Pioneer Murray seems to be a promising find. He appears reasonably sane and vital, unlike other Pioneers Ariadne and Angelo have found, despite having stayed in his habitat trying to gene-engineer a 'companion'. Yet returning him to Earth precipitates a crisis...

Here the novel should have stopped. The scenario envisaged is powerful and rich in potential. It feels like a 'dark reboot' of all the previous optimistic science fiction about space exploration (like for example 'Star Trek'), here inverted into a dying, xenophobic Earth, a failure to spread Earth's 'culture', no FTL drives, no star-spanning empires and no space-faring aliens. Yet the novel keeps going to effect a final upbeat ending. ( )