The Coming of the Quantum Cats
Frederik Pohl
 The novel begins with Nicky DeSota, a timid mortgage broker in a fascist America who draws the unwelcome attention of Nyla Christophe, an FBI agent investigating a break-in at a government lab by what proves to be a Dominic DeSota from an alternate universe. Used as a pawn by Christophe's con-man boyfriend Larry Douglas to entrap an activist former actor (who turns out to be Ronald Reagan), he is later detained and brought to New Mexico to unravel a mystery. The focus then shifts to another Dominic DeSota, a United States Senator having an affair with Nyla Christophe Bowquist, who in this world is a famous violinist. Contacted by the military, he travels to Sandia National Laboratories, where he meets an identical version of himself—a "Cat" from an alternate universe. As Senator DeSota interviews his alternate-universe counterpart, the man vanishes after offering a cryptic warning. As the senator leaves the building, he and the base commander are captured by a detachment of troops led by Major Dominic P. DeSota, the commander of a military force from yet another universe. Major DeSota's mission is revealed to be to secure the parallel-world research facilities of Senator DeSota's universe, which is the first step in a larger military operation. In Major DeSota's universe (which is subsequently designated Paratime Gamma) a militaristic United States is engaged in a tense standoff with the Soviet Union, and wants to use Senator DeSota's universe (Paratime Epsilon) to launch sneak attacks against them. After being transported to Paratime Gamma, Senator DeSota manages to escape by distracting his guard (Gamma's version of Nyla Christophe) and escaping through a portal with a scientist to Paratime Tau—the home universe of Nicky DeSota. After being discovered in the desert, Senator DeSota and the scientist—who is Larry Douglas from another universe—are captured and interrogated by Agent Christophe. In an interrogation session involving the senator, the scientist, and their counterparts from Paratime Tau, Douglas reveals that he is from Paratime Alpha, and that he was forced by the military in Paratime Gamma to give them the ability to travel between universes. As Agent Christophe begins to pressure Douglas to give her government similar assistance, she and the other FBI agent with her are rendered unconscious by knockout darts fired by Dominic DeSota—the same Dominic DeSota who had escaped interrogation in Sandia. DeSota brings the entire group back to his universe—Paratime Alpha—where he explains that since the senator's escape that Paratime Gamma has invaded the Epsilon's Washington D.C. in a failed bid to capture the president. He also reveals that travel between universes is creating a growing problem of "ballistic recoil," where the boundaries between the universes is growing weaker, causing matter and energy to cross unintentionally from one universe to the next (something depicted in interludes between the chapters). He brings the travelers to Washington D.C., where they cross over to Paratime Epsilon in an effort to help stop the invasion. Before they can help, however, every "Cat" located in a different universe disappears, along with any scientists involved in paratime research. There they are informed that they have been transported by a group of more advanced alternate Earths in order to stop ballistic recoil before it escalates and the barriers between universes become irreparably permeable. The "Cats" are relocated to New York City on a new Earth, one being resettled after its inhabitants wiped themselves out. There the paratime transplants gradually settle into new lives. Six months after his arrival, Nicky DeSota returns to New York to propose to Agent Christophe. Now working on a collective farm in Palm Springs, he has embraced the opportunity for a new life and developed into a much more confident man. After considering his proposal, the Nyla of his world accepts. On their trip back to California, however, Nicky reveals to her his expectation that their transplantation has not solved the problem of paratime travel—that with an infinite number of Earths, the number of them that will develop the ability to cross into alternate worlds will only increase, so many that the problem of ballistic recoil may prove to be unavoidable.