With alternative history currently in vogue, among serious historians as well as bestselling novelists like Robert Harris and Harry Turtledove, this collection of 24 tales serves as a timely reminder that Malzberg, author of some 90 novels and 350 short stories, has long been a master of "what if" fiction. The centerpieces here are the three sardonic alternative-world versions of John F. Kennedy's election to the presidency and assassination ("Heavy Metal," "All Assassins" and the title story). A tale like the Hugo-nominated "In the Stone House," in which JFK's ill-starred older brother, Joe Jr., survives WWII to fight another day, cannot help shocking and even offending. Other tales of this type, portraying such varied luminaries as Emily Dickinson, Raymond Chandler, Leonard Bernstein and a Jewish "Christoforo" Columbus, may be less sensational, but are never less than thought provoking. In a different, more whimsical mode, "Prince of the Steppes" features a cabdriver who's a walking bomb and some hilarious Russian spy dialect worthy of Boris Badenov, while "Major League Triceratops" is a somewhat wordy riff on the dinosaur hunt theme. Malzberg's characters flail in an existential world they don't understand, and you may not either, but the challenge is always worth accepting.