Tchaikovsky weaves a masterful tale about how each version of Earth diverged during the various Epochs of its billion-year history. A frozen world computer mind, peaceful brilliant Neanderthals, family-friendly weasels out of a steampunk nightmare, gargantuan spacefaring trilobites, and even feathered dinosaurs combine for a suspenseful joyride through the multiverse.
... [a] tropey, entertaining sci-fi adventure that’s both outrageously bizarre and utterly convincing ... Lee and Julian’s intricate story lines crisscross, building steady momentum and layered suspense ... Edifying and entertaining evolutionary histories of alternate versions of Earth are interspersed throughout, granting the reader insight into the multiverse as the cracks between dimensions widen. Thrilling action punctuates the intrigue on the way to an ending that, though convoluted, satisfies. Sci-fi readers will be pleased.