When an asteroid nearly 600 times greater mass than the one that killed the great dinosaurs and all surface life is about to smash into the Earth, it will bring global devastation. All life will end right down to the smallest single-celled creatures in the depths of the oceans, leaving the Earth a lifeless hulk. How can an asteroid fifty miles across be diverted from its deadly course? There is no way to evacuate over six billion people to another planet in time or to feed and clothe them if there were. As Professor Grymm says, "Even magic has limits." The largest thermonuclear bomb available...

Three ships move outward from Earth with the intent of reaching distant planets to colonize. After a year in space, one of the ships, New Hope 3, finds they are going to have to abort their mission. A course correction would burn up vital fuel they cannot afford to lose. Without it, they will run out of fuel before reaching maximum velocity and the trip to Epsilon Eridani will take a thousand years. Unexpectedly, a wormhole appears dead ahead. Unable to turn away, they suddenly find themselves sixteen and a half light years from home, approaching a very Earthlike planet. All seems to be going...