The comings and goings of a mad right wing assassin and his scientist pursuers through the ""time gate"" (Department of Defense project 237-T) create a temporal traffic jam -- relieved only by passing visits to the alternate futures created by their tampering with past and present. But the contrasting schema for the years 3987-a and 3987-b reveal little about the nature of historical inevitability -- though the assassin's bullet was thought to be a linear cause of the atomic holocaust that followed, its retraction proves to have no reverberations at all. Yet another moment in history (A.D. 2080) turns out to have altered the whole course of human evolution. In spite of being conducted in an intellectual vacuum, the chronological monkey business is mildly amusing, but the personality conflicts of the time travelers border on the ridiculous. Tom ""proves himself"" to his super-critical brother Cal by dismantling the doomsday machine -- surely a sufficient test of manhood, and in the course of his travels acquires a bride willing to adapt to life in the 1980's with never a backward (or forward) glance. A naive and futile exercise in the stretching of time-space coordinates.