There are too many men in a world governed by women. They're bored and disillusioned and often resort to 'suicide missions' - jobs in experimental space research. Jorn applies for such a job, is selected and trained as a navigator for the huge ship Javelin, the first to implement the recently discovered faster-than-light Evrak Effect.

Before the Effect is tested, however, it is discovered that life will be extinct within nine years; the sun is burning up, preparing to explode. The Evrak Effect will save a small percentage of mankind, take civilisation to a yet unknown planet. Production on new ships is given priority, the ruthless selection of passengers begins. Twenty-five billion people will be left behind.

Led by Javelin, thirty ships wander in space through many light years of promises, lost hope and death for the original crew and passengers. But life does survive, children grow and learn, to inherit the beginning of another world, another promise.

James Blish has written a compelling novel of gigantic moral problems and of people who learn to cope with their own limitations in order to deal with them.