The year is 2040, and in the Solomon Islands a programme to breed genetically-modified dolphins with near-human brains is underway. Dawn, a girl from England on a visit to the Solomons, suffers strange hallucinations when she encounters the dolphins, in which she is transported by means of a spirit journey into a parallel universe. It transpires that she too has been genetically modified, not by humans but by benign aliens from this parallel universe, so that her brain, as it reaches maturity, becomes like theirs.

An unintended consequence of the dolphins' neural modifications is that they are telepathic and are able to journey into this parallel universe. The intention of the aliens is that Dawn should play a key role in the development of dolphin culture. However, other malign aliens from the parallel universe have made contact with a sinister religious cult bent on world domination. The battle that ensues between Dawn's dolphins and these malign forces takes place in both this and the parallel universe. Set against this backdrop is the romantic attachment that grows between the leader of the dolphin community and one of the humans caught up in the conflict.