"On Saudi Arabia," by Karen Elliott House In Peter Berg's whodunit "The Kingdom," a young F.B.I. agent boarding a plane to Riyadh asks a seasoned colleague what Saudi Arabia is like. "A bit like Mars," replies the more experienced man. It's not Mars, exactly, but for most Americans Saudi Arabia is probably more like another world than any other inhabited part of this one. It is about as distinct from the freewheeling United States as a country can be - not a modern totalitarian "republic" like Communist North Korea, but another kind of dictatorial regime, a fanatically conservative society self-oppressed by thousand-year-old rules, regulations, prescriptions and prohibitions. The Kingdom of Saudi Arabia is, as Christopher Hitchens once described the occluded realm ruled by the Kim family in Pyongyang, a place "where everything that is not absolutely compulsory is absolutely forbidden." The Pulitzer Prize-winning journalist Karen Elliott House has been visiting the kingdom for more than 30 years, and in her new book, "On Saudi Arabia: Its People, Past, Religion, Fault Lines - and Future," she skillfully unveils this inscrutable place for regional specialists and general readers alike. "For millennia," she writes, "Saudis struggled to survive in a vast desert under searing sun and shearing winds that quickly devour a man's energy, as he searches for a wadi of shade trees and water, which are few and far between, living on only a few dates and camel's milk. These conditions bred a people suspicious of each other and especially of strangers, a culture largely devoid of art or enjoyment of beauty. Religious edicts are crushingly enforced by state, mosque and society. Movie theaters are banned, as are concerts and just about everything else related to entertainment. Women, even foreign women, must cover themselves in public. Unrelated women and men aren't allowed to mix anywhere. Even Starbucks coffee shops­ are segregated by gender. Men have it rough, but women have it much rougher. According to Wahhabi Islam, men must obey Allah and women must obey men. "Fortunately for men," House writes, "Allah is distant, but unfortunately for women, men are ­omnipresent." Western women like House, though, have an advantage, despite the fact that they're forced by the Muttawah, the religious police, to cover themselves. In Saudi Arabia they are treated as "honorary men," so House was able to interview whomever she liked - men and their wives, women and their husbands - something no foreign man or Saudi citizen of either gender is ever allowed to do. She describes the society as a maze "in which Saudis endlessly maneuver through winding paths between high walls of religious rules, government restrictions and cultural traditions." The labyrinth is not just a metaphor. Cities are claustrophobic places where even men but especially women live as shut-ins, socializing strictly with family. Walk down a residential street and in every direction you'll see not porches and yards but walls "that block people from outside view but, more important, separate them from one another." And the country as a whole is riven with virtual walls. The sterile interior highlands of the Nejd are at odds with the relatively cosmopolitan Hejaz on the coast of the Red Sea. In the Eastern Province, where the country's oil reserves are concentrated, Shia Muslims live under the boot, denounced by Wahhabis as heretics. The Ismailis in the destitute south, with their historic links to Yemen, are not-so-benignly neglected. Each of these regions in turn is divided by tribe, and each tribe is divided by family. Most Saudis marry one of their cousins. Hardly any of them marry outside their tribe, let alone region. But the highest wall of all - the information barrier restricting knowledge of the wider world and its ways - is crumbling fast. Thanks to the Internet, the young (and 60 percent of Saudis are 20 or younger) know all about life in less cloistered Arab societies and in the West. And they're not buying into the Saudi system the way their parents and grandparents did. Michael J. Totten, a contributing editor at World Affairs and City Journal, is the author of "The Road to Fatima Gate" and "Where the West Ends."