The book depicts the arrival of members of an alien species called the Fithp that have traveled to the Solar System from Alpha Centauri in a large spacecraft driven by a Bussard ramjet.

An arms race between two rival herds threatened to render the species extinct, so they wagered to see who would depart in a starship and seek a new home elsewhere.

The original leaders are subordinate to the Spaceborn, who are prepared to start a space-based civilization, but are still dedicated to the generations-old goal of conquest.

Civilians are used to show the effects of the war on day-to-day life in the US, and military and government personnel convey a more strategic overview of events.

The Fithp, who are familiar with nuclear weapons, but prefer to use cleaner ones, are shocked by what they consider the barbarity of humans' willingness to "sow radioactive fire on their own croplands".

The Fithp respond to the defeat of their invasion by dropping a large asteroid into the Indian Ocean, whose impact results in environmental damage on a global scale, particularly the almost total destruction of India.

The US secretly builds a large, heavily armed spacecraft in Washington state that is propelled by nuclear bombs, a real concept known as Project Orion.

When Coffey seemingly folds under the pressure, National Security Adviser Admiral Carrell stages a bloodless coup d'état, circumventing the President and rejecting the aliens' proposal.

It judged the novel to be "more tedious and less thoughtful" than previous joint Niven–Pournelle works, with "barely relevant" subplots and a "cumbersome cast of thousands" but praising the Fithp society as "particularly well worked-out.