Dara Horn’s fourth novel is one of those enthralling, excessive works so stuffed with ideas and images as to be sometimes maddening. “Why,” I found myself asking, “do we need to meet Maimonides himself?” The 12th-century philosopher turns up two-thirds of the way through this novel, when the story is already toggling between contemporary and 19th-century time frames, both featuring a key role for Maimonides’s treatise “Guide for the Perplexed.” And Horn’s narrative prompts other exasperated questions as well: Must there be fraught sibling relationships (plus someone with asthma) in all three story lines? Do the echoes of the biblical tale of Joseph and his brothers significantly enhance the novel, or are they window-dressing? Oops — better not bring windows into it, or we’ll be building a whole metaphorical house, given the prevalence of doors in Horn’s intricate web of imagery.

I’m being slightly unfair to this abundantly gifted author, and I should stress that anyone who cares about the art of fiction will want to read “A Guide for the Perplexed.” The central story is riveting and closely tied to debates about privacy and electronic surveillance. Massachusetts software designer Josie Ashkenazi has invented Genizah, a program that employs computers and mobile devices to automatically record everything users do, allowing them to access any moment in their past. This rather sinister system, which bears the Hebrew name for a synagogue’s storeroom for damaged books, has made 33-year-old Josie a very rich woman. It’s also made her older sister, Judith, “sick with envy.”

Shortly after the novel opens, Josie is kidnapped and apparently killed in Egypt. Judith moves into her sister’s house and is soon sleeping with her husband. But a few months later, a text message arrives: “im still here don’t tell anyone come get me love josie.” What will Judith do?

Judith’s betrayals of Josie go back 20 years, to an afternoon at summer camp when she let a group of girls taunt her nerdy sister into climbing down into a pit, and then left her there after dark. But the vision Josie had in that pit — hundreds of little doors, each one opening onto a memory — ultimately led her to invent Genizah.

Now, held by rebels in Egypt, Josie is ordered to create a virus that will disable the Cairo police’s Genizah database. As she works, she begins to see a difference between real memories and the artificial reality stored in her software. If she ever gets free, what will Josie do with Genizah?

“A Guide for the Perplexed” by Dara Horn. (W. W. Norton)

This is extraordinary material, emotionally resonant and intellectually suggestive, and Horn’s portraits of the sisters are wonderfully ambiguous. Josie is arrogant and addicted to admiration; Judith understands people much better — the better to manipulate them to her own ends. Josie’s interactions with her principal kidnapper are equally complex. The brutal man whose beatings have made her “his dog, his slave” is also the grieving father who asks her to “make a Genizah” of his dead son.

It’s wrenching to be pulled away from such a gripping tale to the more leisurely story of a scholar named Solomon Schechter, who discovered the Cairo Genizah in 1896. But it’s a nice touch that this hodgepodge cache of medieval manuscripts, including business receipts and medical prescriptions, foreshadows the indiscriminate data collection of Josie’s 21st-century Genizah. And Horn draws disquieting parallels between Schechter’s efforts to unlock the code of Egyptian manners (so that a local rabbi will show him the Cairo Genizah) and Josie’s desperate need to decode her captors’ motives, coupled with the grim knowledge that when she finishes writing the computer code they want, they’ll kill her.

Horn has always been fond of intricately braided story lines, and this book, like her 2006 novel, “The World to Come,” interweaves historical and contemporary tales to create intriguing echoes and layers of metaphor. Maimonides, however, is one parallel and many metaphors too many. Horn’s perennial concern with the ethical and spiritual questions embedded in Jewish traditions was seamlessly integrated into her best novel, “All Other Nights.” Here, when Josie begins reading “Guide for the Perplexed” after her kidnappers take away the computer each night, the lengthy extracts of Maimonides’s views on divine providence are obvious and overbearing. Worse, Maimonides’s life story is jarringly inserted into the novel just after Judith boards a plane for Cairo to look for her sister.

These interpolations feel unnecessary because Horn’s searing family drama easily encompasses whole worlds of political, philosophical and moral conflicts all by itself. We see how capacious the sisters’ story is during the climax in Cairo and eight years later in the chilling conclusion, which shows old patterns being reproduced. Beautifully written and overwhelmingly sad, the final monologue by Josie’s daughter concludes a flawed novel whose ambitious failures are in every way more interesting than the perfections of a small, safe book.

Smith is a frequent reviewer for Book World who lives in New York.


By Dara Horn

Norton. 342 pp. $25.95