In a future hammered by climate change and drought, mountain snows have turned to rain, and rain evaporates before it hits the ground. In a fragmenting United States, the cities of Phoenix and Las Vegas skirmish for a dwindling share of the Colorado River. The Las Vegas water knives - assassins, terrorists and spies - are legendary for protecting Las Vegas' water supplies, and for ensuring Phoenix's ruin. When rumours of a game-changing water source surface, Las Vegas dispatches elite water knife Angel Velasquez to Phoenix to investigate.