After a mysterious red rain blankets Earth, few rational humans remain, including John’s family. John leads a small group of survivors to The Isle of Lewis off the coast of Scotland. Multiple threats loom, including reject-humans, reject-dogs, and a contingent of government officials from London that arrives at the compound on the Scottish island.

Mysteries abound, including why all of the young adult female survivors are pregnant, and why the government officials deny what rogue Dr. Shaw, a quirky geneticist, describes to those who have followed him to this government facility. Based on the information Dr. Shaw gleans from the lead MI6 agent, he encourages John, a petroleum engineer, to return to the oilrig in the North Sea where he used to work in order to fend off the next alien harvesting.