The problem with having written as many great works of science fiction as Frederick Pohl has is that sometimes that opus can overshadow a title or two. While not entirely neglected, this novel is usually not ranked alongside such classics as 'The Space Merchants,' 'Gateway,' and 'Jem'. Perhaps it does not measure up to these works, but it is nonetheless an enormously enjoyable book.
Set in the then-contemporary world of 1983, the novel follows the different incarnations of three characters - Dominic DeSota, Nyla Christophe, and Larry Douglas - as they deal with their counterparts from alternate worlds. Pohl uses the premise to posit some very different Americas, but the real focus is on the very different people these characters became within these worlds - one Dominic is a senator, another is a meek mortgage broker, a third a major commanding an assault force. These characters confront each other as their different timelines clash - and face the increasing danger posed by the unintended consequences of travel between their worlds.
The greatest strength of the book is not in the alternate worlds Pohl describes (many of which are satirical takes on the America of his day) or in his use of historical personages, but in the characters he creates. Though his premise is based on developing different permutations of just a few individuals, he nonetheless makes each of them distinct and interesting. Through them the reader is offered an interesting mediation on how different circumstances can shape character - all within the context of a novel that ranks with the best works of alternate history.