Gwyneth lives in a mansion with her extended family, including an elegant cousin, Charlotte, who is being groomed for a future imagined as “dancing with Mr. This is not the first time her uniform has “been drenched in sauce, juice or milk.”

The book opens with Gwyneth, a 16-year-old London schoolgirl, overlooked and a little clumsy, spilling her lunch on her shirt. The storytelling is fluid, and Gier is both clever and funny: “There was always some horrible thing lurking” in the past - “war, smallpox, the plague.” It’s just that quantum physics isn’t the point. This is not to make “Ruby Red” sound inane. Knotty technical questions only elicit bewilderment: “The longer you thought about this time travel stuff, the more complicated it got.” It’s about journeying back to the past with a really hot guy. Gier also writes best-selling women’s novels with titles like “Men and Other Disasters,” and her genial, comic sensibility informs “Ruby Red.” Time travel, Gier style, is something to be discussed on the cellphone while standing in the yogurt aisle at the supermarket.

Neither cerebral like Madeleine L’Engle’s time travel classic “A Wrinkle in Time” nor literary like last year’s Newbery Medal winner, Rebecca Stead’s “When You Reach Me,” this is more like chick lit sci-fi.

The best answer is that “Ruby Red” is both suspenseful and comforting. What is it about this book that inspires such enthusiasm? One amateur translation attempt posted online, while less expert than that of the book’s award-winning translator, Anthea Bell, was somehow more stirring: I pictured a teenage girl sitting at a desk in her bedroom, holding her copy of “Rubinrot” open in one hand, mouthing a few words, then turning to her keyboard to share it with the world. “Ruby Red” has the kind of fans who upload videos of themselves performing scenes from the book on YouTube (as part of a casting contest for a film in preproduction). Already a phenomenon in Germany, where it was published in 2009, “Ruby Red,” the first installment in a time travel trilogy by Kerstin Gier, is now making its American debut.

The ruby red trilogy kerstin gier