Cambridge, Massachusetts, Ourverse, September 10, 2010. Scientists Mark and Morgan, working at MIT to create new and powerful sources of energy, have originated a method for moving between alternate universes. Twenty years earlier they warn the government of an impending rupture of the border separating the universes. The government, unbelieving, warns them to cease their experiments or suffer extreme consequences. Mark I and Morgan I do not understand that their alter-egos, Mark II and Morgan II, are doing the same thing. The techniques used by the alternate scientists, however, are using a flawed set of equations. This means that their prototype acts as a triggering mechanism to prematurely push the two systems into dangerous and potentially destructive conjunction. The "Ourverse" Mark I and Morgan I are, as a result, pulled into "Paraverse" where their alternates have not discovered the impending disaster and are busy attempting their maiden voyage across universes. The children of both sets of parents are vulnerable, which adds a strong element of anxiety to the efforts of Mark II and Morgan II. Unfortunately, the original Mark and Morgan do not remember who they are, what they were doing, or even that they are married when they come to in separate places at Rockefeller Center in Paraverse. They cross paths and travel together, becoming romantically drawn to each other, the wedding rings on their hands suggesting to them that they are married to others. Having disobeyed the government, assassins from their home universe, Ourverse, are sent to kill them, as the government of Paraverse suspects them of being aliens that are causing the rift between universes and sends out virtually indestructible assassins injected with regenerating nanotechnology. As they stumble blindly into a series of encounters, conflicts, and disasters, the two systems draw closer and closer together, and as a result people are suffering terrible changes, merging with animals and other non-human things. Twinned bridges between Manhattan and Queens pull together with disastrous results. Worst of all, should an individual and his (or its) identical alternate meet and touch each other they are mutually destroyed. At last Mark I and Morgan I regain their memories and realize they must go to MIT and find a way to halt this terrible meeting of worlds. As they struggle to make their way to their lab a CIA assassin is converted to a helper once he understands the real situation. Complete strangers unite to help them, as well, some losing their lives as they work. When at last they do reach the lab, they discover a terrible aspect of their existence and are confronted with a nightmarish remedy which will re-balance the systems. Only then will their worlds be stabilized.