Shame on Koontz for following up his best chiller yet (the exciting, inspired Watchers) with this erratic popcorn that nearly buries its neat premise--time travelers from the past shadowing a woman's life--under soap operatics more absurd than any purveyed in his earlier novels. Strange is the childhood of Laura Shane: a blond mystery man saves her at birth from a drunken M.D., then turns up eight years later to save her and her shopkeeper dad from the hands of a crazed junkie. And Koontz matches this mystery with another: enigmatic scenes of ""the guardian""--""Stefan""--being tailed, and of his wiring for detonation the institute where he works. An enticing setup; but Koontz too soon sours these parallel puzzles with three-hankie melodrama. Laura's dad dies, so she's sent to an orphanage where she befriends a pair of twins but is menaced by a child-abusing aide with the Dickensian name of Sheener. In time, Laura slays Sheener in self-defense; but a fire kills one of the twins. Laura and the other twin, Thelma, bond and grow into fairy-tale destinies: Laura--who marries and has a son--becomes the nation's #1 novelist, while Thelma reigns as the #1 comedienne. Meanwhile, Koontz reveals that Stefan is. . .a time-traveling Nazi attached to an experiment aimed at grabbing an atom bomb for Hitler, but Stefan has fallen in love with Laura (he read her books during one of his time-trips); hence his twinkling into her life at critical times. And he's a good Nazi, too: he hates other Nazis and wants to destroy the institute (thus the tail on him--a suspicious security man). Once Stefan and Laura join forces (more time-traveling Nazis kill her husband), Koontz thankfully drops the suds for a rousing chase, with Laura showing great spunk in eluding and icing Nazis, and with Stefan jet-setting between past and present (and meeting with Churchill and Hitler) as the action chums to its frothy, bittersweet end. Despite patches of lickety-split narration and clever use of the time-travel theme, this uneasy amalgam of romance and chiller is second-rate Koontz (and closer in spirit to the contemporary-Gothic paperbacks he writes under the Leigh Nichols byline than to his other work). Still, Laura's a winsome heroine and her storybook adventures will probably appeal to most of Koontz's ever-growing legion of fans.