With his epic novels of alternate history, Harry Turtledove shares a stunning vision of what might have been—and what might still be—if one moment in history were changed. In the WorldWar and Colonization series, an ancient, highly advanced alien species found itself locked in a bitter struggle with a distant, rebellious planet—Earth. For those defending the Earth, this all-out war for survival supercharged human technology, made friends of foes, and turned allies into bitter enemies. For the aliens known as the Race, the conflict has yielded dire consequences. Mankind has developed nuclear technology years ahead of schedule, forcing the invaders to accept an uneasy truce with nations that possess the technology to defend themselves. But it is the Americans, with their primitive inventiveness, who discover a way to launch themselves through distant space—and reach the Race’s home planet itself. Now—in the twenty-first century—a few daring men and women embark upon a journey no human has made before. Warriors, diplomats, traitors, and exiles—the humans who arrive in the place called Home find themselves genuine strangers on a strange world, and at the center of a flash point with terrifying potential. For their arrival on the alien home world may drive the enemy to make the ultimate decision—to annihilate an entire planet, rather than allow the human contagion to spread. It may be that nothing can deter them from this course

The novel is set in 1963, eighteen years following the end of the alternate World War II shown in the Worldwar series. Earl Warren is President of the United States, Vyacheslav Molotov is the Premier of the Soviet Union, and Heinrich Himmler leads Nazi Germany. At the start of the novel, the colonization fleet of the Race enters the Solar System, bringing with them, forty million colonists for settling on Earth. As the fleet enters Earth orbit, a human satellite unleashes a nuclear attack that kills millions. As Germany, the USSR, and the United States each have large-scale space capability, either nation may have been responsible for the attack. In addition, while there is peace between the independent human nations and the Race, Mao Zedong and Ruhollah Khomeini continue to lead popular resistance to the invaders in China and the Middle East, respectively. Meanwhile, the Race colonists, who expected to encounter an Earth that was already conquered with the natives still at medieval levels of advancement, have to deal with the consequences of the cold war with the humans. The fleet brings with it not only the first civilians, but also the first Race females, both of which cause tension among the male soldiers who formed the invasion force. To the Race males, ginger is a euphoric drug; to the females, it causes them to go into estrous, resulting in wide-scale social implications

Following the nuclear attack on the colonist ships in Second Contact, the Race continues to try to find the responsible nation, along with the purpose of the Lewis and Clark, a large space station launched by the United States. At the same time, the range animals brought by the Race colonists begin to spread into the human nations, causing ecological trouble and causing conflicts between them. Meanwhile, in the Soviet Union the NKVD under Lavrenti Beria attempts to launch a coup against Vyacheslav Molotov, but is thwarted by Georgi Zhukov. In Nazi Germany, Heinrich Himmler, the Fuhrer, dies and is replaced by Ernst Kaltenbrunner. Kaltenbrunner, angered by the policy of accommodation Himmler carried out towards the Race, including his refusal to invade Race-occupied Poland, causes him to initiate a nuclear war between Germany and the Race

The nuclear war between Nazi Germany and the Race ends with a Germany surrender after Ernst Kaltenbrunner, the Fuhrer, is killed and replaced by Walter Dornberger. Dornberger agrees to disband the Axis Forces, withdraw German troops from occupied France, and disband the German rocket and nuclear forces. The German withdrawal results in instability in the governments of its allies, such as the British Union of Fascists in Britain, as well as clashes between the Free French Forces and the new government of liberated France and radioactive drift into the Soviet Union. However, Dornberger secretly begins stockpiling weapons and missile parts, allowing Germany the option to rearm itself in the future. Meanwhile, the nuclear attack on the Race's colony fleet from Second Contact is finally revealed: it was an American attack, ordered by Earl Warren. When it is revealed, Fleetlord Atvar gives Warren a choice: dismantle the American space program, or allow the Race to nuke Indianapolis for revenge. To the surprise of all, Warren allows the Race to destroy Indianapolis, and then commits suicide, with Vice President Harold Stassen taking over. It is eventually stated that the reason Warren allowed the city to be destroyed over the space program was that the Americans were working on a starship that would allow them to journey to the Race's homeworld and repay their visit to Earth. During this time, the Race itself undergoes large social unrest, due to the effects of ginger on their females. Drug addiction, the black market, and prostitution all arise from it, along with a reproductive system that is unregulated, much like that of humans