In 1880, British author Edwin A. Abbott pseudonymously published Flatland, a classic fictional thought experiment about life in a two-dimensional world of intelligent polygons. In the latter half of Flatland, the "author," A. Square, is visited by a sentient Sphere, which takes him to a three-dimensional universe called Spaceland and attempts to communicate the difficult concept of "height." Mathematician and longtime science-fiction wonk Rudy Rucker takes the next logical step with Spaceland. Borrowing Abbott's structure and terminology to fuel a similar thought experiment, Rucker begins with a concrete, recognizable modern world, then bends it into the kind of extremes he reached in such frenetic, twisty fantasy-tech books as the Gnarl! anthology and the Live Robots series. Early on New Year's Day 2000, a Silicon Valley dot-com manager with the odd name of Joe Cube is visited by Momo, a fourth-dimensional woman with a business proposition: She wants him to start building and marketing fourth-dimensional technologies. To facilitate her project, she "augments" him with the ability to see and even travel into the fourth dimension. Joe—a shallow, selfish yuppie whose imagination and empathy is so poor that he uses a sexual-frequency spreadsheet to determine when to "turn on the charm" with his equally shallow, selfish wife Jena—quickly gets over both his fear and his astonishment, and falls into a pattern of indiscriminate, though somewhat sulky, obedience. Once he convinces Jena that he can see through solid matter by visualizing the world from outside the normal three dimensions, she decides that the best possible use for his power involves breaking the bank at Tahoe by cheating at blackjack. Soon, Joe is struggling with angry casino thugs, his wife's infidelity, and another interfering fourth-dimensional creature, in addition to an increasingly dangerous Momo, but he lets threats and the prospect of a wallet-fattening IPO outweigh his better judgment. Like Abbott before him, Rucker leavens the mind-bending theoretical aspects of his novel with humor, a sense of creative exploration, and some social satire, but he also adds wildly imaginative and well-conceived flights of descriptive fancy. As usual, however, Rucker's human characters are his weakness. Mercurial and moody, with allegiances and desires that take 180-degree turns on an hourly basis, Joe seems tailor-made for Momo's manipulations, but his wife and co-conspirators are equally lightweight, and they all get caught up in the plot like wood chips in a hurricane. Still, for one of Rucker's lunatic yarns, Spaceland is unusually sedate, with a respectable balance between conceptual creativity and comprehensible execution. A fun yet thoughtful read, the book gives an appropriate new sense of dimensionality to Rucker's work.