The Dream of the Iron Dragon, Paperback

It is the year 2207. After a decades-long war with an alien race known as the Cho-ta'an, Earth has been rendered uninhabitable and the human race has been driven to the brink of extinction. Humanity survives in a handful of colonies scattered across the galaxy, connected by hyperspace gates. Things look dim for the human race when the crew of a scientific survey ship comes into possession of an incredibly destructive "planet-killer" bomb left behind by a long-extinct alien race. With this weapon, the human alliance could threaten to destroy the Cho-ta'an homeworld, changing the balance of the conflict. But as the ship travels through a hyperspace gate to deliver the bomb to the alliance command, a fluke warping of spacetime send them 1300 years into the past. Stuck in 885 A.D., its engines damaged, the vessel is powerless to deliver the bomb to the human alliance. While the rest of the ship's crew remains in stasis, a small landing craft, led by an engineer named Carolyn Reyes, is sent to Earth to fabricate a part needed to repair their ship's engines. But the craft is intercepted by the Cho-ta'an ship and shot down. It crash lands in a snowy, mountainous region and the crew is beset by a band of people wearing primitive clothing and wielding weapons made from iron and wood. Reyes's crew barely escapes, and their landing craft is torn apart. The newcomers finds themselves embroiled in the local politics, and soon join a group of locals fleeing the tyrannical rule of a king named Harald Fairhair. But Reyes is not content merely to survive. Knowing that humanity's future depends on repairing their ship, she determines to complete their mission. Thus begins a decades-long effort to build a craft capable of returning to space-a ship that will come to be known as the Iron Dragon.