When Ben Bova started his Voyagers saga in 1981, the world and his depiction of it were obviously quite different from the way they manifest in 2009, as the fourth volume in the series surfaces nearly 20 years after the third (Star Brothers, from 1990).
How to reconcile any improbabilities between yesterday's tomorrows and the up-to-date scenario Bova wants to examine now? Easy enough! Bova has his protagonists accidentally jump laterally across the multiverse to another timeline than the one they started in. Now that's a handy drift!
In any case, our tale, The Return (Tor, $25.99), concerns the reappearance of star traveler Keith Stoner, his wife Jo and their kids, Cathy and Rick. After their encounter with alien tech, the family has assumed super-science powers such as mind-reading and teleportation. Arriving at a dystopian Earth on the point of destroying itself with nuclear war, they feel compelled to help rescue the race from self-destruction. But as Stoner ruefully acknowledges, compulsion is a dead end. Only re-education can make for a stable future. Trouble is, "Against stupidity the gods themselves contend in vain."
As Stoner deals with various power blocs on Earth, from the U.S. religious dictatorship known as the New Morality to their counterparts, the Islamist and Chinese dunderheads, as well as with the more enlightened spacers on the moon and around the Jovian worlds, he has transformative impacts on a variety of folks, from Sister Angelique, an ambitious politico, to Raoul Tavalera, a common-man type who finds himself sacrificing his own happiness for the good of the species. Stoner comes across as a believable human-turned-demigod, but his family, garnering less screen time, remains rather unformed.
Combining elements of Lost in Space (1965), The Day the Earth Stood Still (1951), The Man Who Fell to Earth (1963) and 2001: A Space Odyssey (1968), Bova's conclusion to his quartet (and it does seem like a pretty definitive ending to me) offers little in the way of fresh speculation or thematic lessons that the genre has not trafficked in for decades. But dramatic counsel about the consequences of pigheadedness and shortsightedness is always a valuable, timeless offering from the SF genre.