College professor Lyle Peripart, the descendant of American expatriates, tries to ignore the various Reichs that rule the world following the Axis victory in WWII over a century ago, until the powerful industrialist Geoffrey Iphwin, interested in Lyle’s clever statistical analyses, hires him. After the interview, he’s beaten and interrogated by the fearsome female Gestapo operative, Billie Beard—but her questions are baffling. Stranger still, it emerges that Lyle managed to be in two places at once: while he was being interviewed, he was also flying to Saigon with his fiancÇ, Helen Perdita. Shrugging, Lyle joins Helen in Saigon, where a fat German tourist tries to assassinate him. Helen, suddenly packing a pistol, blasts the assailant—who turns out to be Billie Beard! Moreover, Helen now denies she can shoot, and claims she saw Lyle killed. In the history she remembers, the Allies won WWII, but America lost a nuclear war in the 1980s. Confused? According to Iphwin, since the introduction of quantum computing devices, every time someone uses a phone, or switches on a computer, he or she jumps into another reality, of which there are an infinite number. Iphwin himself is a human avatar of a “cyberphage,” an artificial intelligence patrolling the realities as a sort of super System Administrator. Even more puzzling, America has disappeared from every reality: just trying to think about it causes pain and confusion. The cyberphage wants to know why. The opposition—Billie Beard is its avatar—is cleaning up the system by killing anyone who knows anything. Eventually, we learn why America disappeared and, disappointingly, how it all comes out. From the author of Earth Made of Glass (1998), etc, a virtuoso piece of probability-juggling that mostly adds up—until that dreadfully anticlimactic non-ending brings you back to, er, reality with a thump.