In the early years of the 21st century humanity has advanced into space, but has discovered that certain asteroids have changed their orbits and are headed for a horrifying impact with Earth. But there is a world financial crash, and politics get in the way of progress, requiring the cast of characters introduced in the earlier books to pull together and save humanity from disaster.

With great difficulty, serious preparations begin to reach the asteroids and destroy or divert them, and culminate in a long, exciting voyage out to the asteroid first visited in Rogue Star, where an alien control room was discovered.