Paolo Bacigalupi’s near-future thriller, The Water Knife, tells the story of Angel Velasquez, a “water knife” working for the state of Nevada trying to infiltrate and destroy Arizona’s water supply and investigate rumors of senior legal rights to water from the Colorado River. The novel cycles between three points of view: Angel; Maria Villarosa, a Texas refugee; and Lucy Monroe, an award-winning journalist.

Water is becoming increasingly scarce, and now individual states in the United States fight each other for access to it. Dust storms threaten to engulf the US Southwest. States like Texas and Arizona have all but collapsed, forcing those citizens to become refugees. Other states like Nevada and California battle for a greater share of the Colorado River. State militias murder those refugees who attempt to illegally cross the Colorado. Meanwhile, the wealthy can buy themselves housing in new luxury arcologies, which recycle water and are furnished with lush vegetation, keeping out the harsh desert.

As a water knife, Angel’s job is to strategically cut the water from rival towns and cities for his boss, Catherine Case, the “Queen of the Colorado.” In Phoenix, Angel meets up with Julio Gúzman, another one of Case’s agents. Together they investigate the murder of James Sanderson, a legal associate with Phoenix Water. Jamie also happens to be a friend of Lucy, and the three encounter each other while viewing Jamie’s mutilated remains.

Meanwhile, Maria and her friend Sarah are desperate to make enough money to pay rent to the Vet and his gang of thugs that own the surrounding neighborhoods. Sarah convinces Maria to sleep with Michael Ratan, a wealthy man involved in water excavation. Sarah assures Maria that Ratan will pay them the money they need to escape Phoenix. The morning after Sarah and Maria sleep with Ratan, Ratan gives Maria a copy of Cadillac Desert. Maria doesn’t know it at the time, but the senior water rights that Angel is looking for are tucked inside the pages of the book. Sarah and Ratan are later murdered in the apartment while Maria hides under the bed from the killers. Maria doesn’t see the killers’ faces, but she notices a tattoo on one of the hands that reaches under the bed to search the room. Angel, following up on a lead, enters the apartment after the killers have left and finds Maria there. The two escape the arcology together after Angel notices that “Calies,” agents from California, are following them. Later, Maria tells Angel about the man’s tattoo. Angel understands that the tattoo Maria is describing belongs to his partner, Julio.

Angel finds Julio at a safe house as he is torturing Lucy, trying to get information out of her as to the location of the senior water rights. Julio has been double-crossing Case and looking to sell the senior water rights on his own to the highest bidder. Angel is forced to kill Julio in a shootout, but not before Angel is shot and injured.

Lucy and Angel attempt to open Ratan’s encrypted laptop, believing the senior water rights to be on his computer. Lucy gives the laptop to her photographer friend, Timo, who knows some people who might be able to crack the encryption on the laptop. However, David Kota, a man working for California, gets to Timo first and flips him. Kota arranges a meeting with Lucy and makes a deal with her: deliver Angel in exchange for the safety of her family. Lucy agrees to deliver Angel to the Calies. At a gas station, Angel discovers that his cash card has been deactivated. Case now suspects Angel of double-crossing her. In the parking lot of the gas station, the Calies’ assassination attempt on Angel starts a firefight that engulfs most of the surrounding area. Angel is critically wounded after the encounter, and even though Lucy set Angel up to be assassinated, she still cares for him and decides to save his life.

Meanwhile, the Vet is torturing Maria for failing to pay rent on time. He feeds her hand to his hyenas, and she remains caged inside of his compound. The Vet and his men notice the smoke rising from the fire started at the gas station and leave the compound in a hurry to join the fray. Toomie, Maria’s friend who tried to protect her from the Vet, discovers her at the compound and frees her. Maria decides to attempt to cross the Colorado River on her own.

Angel and Lucy make it to another Las Vegas safe house. Angel places a call to Las Vegas pretending to be helpless and in need of extraction. Angel and Lucy relocate to another building and watch as a helicopter blows up the safe house with two missile strikes. After the smoke clears, Angel and Lucy ambush the men searching for Angel’s body in the rubble. Angel discovers that Case is working with California to secure the water rights from Angel, whom she believes is withholding them from her. Angel attempts to convince Case that he never double-crossed her and that he will bring her the water rights.

Angel and Lucy track down Toomie and ask him about Maria. Toomie leads Angel and Lucy to the spot where Maria attempted to cross the Colorado River. Angel finds the water rights with Maria and promises that he can get all of them into the arcology in Las Vegas when he presents the documents to Case. Lucy, however, believes the rights belong to Phoenix and attempts to leave with the rights at gunpoint. Angel decides to let Lucy go, but as Lucy tries to leave with the rights, Maria shoots her. Angel speculates that Lucy may survive once they bring her back to Las Vegas. Helicopters are sent to extract the group and bring the water rights to Las Vegas.