Paolo Bacigalupi’s The Water Knife is a smart, fierce, propulsive thriller and an unsparing look into a future that seems all too real. In this book’s timeline, drought and climate change have devastated the American Southwest; Texas has basically gone to hell, and other states are waging something close to literal war over access to water from the Colorado River. The borders are shut down—state borders, that is. Nevada doesn’t want drought refugees from Arizona, Arizona doesn’t want refugees from Texas, and California (powerful and still water-rich) doesn’t want the poor from anywhere else. Borders are enforced with fences, checkpoints and state militias. The lucky rich live in enclosed “arcologies”—self-sustaining luxury towers with greenery and waterfalls, fed by recycled water and sealed off from the outside world. In this gritty, dust-blown future, the stories of three characters intersect. There’s Angel Velasquez, hired gun for the corrupt Southern Nevada Water Authority (SNWA...