The author of The Broccoli Tapes (1989, ALA Notable), plus several other perceptive novels depicting young people coping with various challenges, uses time-travel in a story of two cousins, each mourning the loss of a parent. Linny agonizes over having angrily abandoned his mother Josie, just before her death, to go to a skateboard competition; Hilary, pining for her adored father, blames her mother, Helen, for their divorce. Vacationing at Helen and Hilary's new Vermont home, the two 12-year-olds are transported (by a brass ring they find) to their old Brooklyn neighborhood—a year ago, three days before Josie died. There, Hilary confronts the truth that her Dad was involved with another woman; but Linny—though his feelings are again complicated by the need to prove himself on the skateboard, and by the pain (and boredom) of caring for his cranky mother—does have an affectionate parting with her before he and Hilary slip back to Vermont. The cousins are likable and well drawn, and Slepian uses some time-travel paradoxes to intrigue fans (older and wiser, Hilary and Linny find prescience uncomfortable), but there are cracks in her logic—e.g., Hilary is unbelievably unconcerned about her aunt's imminent death, and why there aren't two Linnys in Brooklyn goes unexplained. Still, there's entertainment here, plus some thoughtful underpinnings. (Fiction. 9-12)