One could argue that in the era of Covid-19, Bohjlian's novel about plague-ridden rats is eerily prescient. Yet the psychological tensions and complex implications of the plot are what really drive this powerful novel. Alexis and her new boyfriend, Austin, are on a biking tour in Vietnam when Austin goes missing. Alexis is reluctantly tasked with the duty of finding him. A New York emergency room doctor, Alexis is used to handling trauma. It is there that she first meets Austin, who comes into the emergency room one night with a low-velocity gunshot wound. Alexis is captured by Austin's ironic smile and boyish, rakish looks.

In her hotel room in Vietnam, panicked Alexis makes a list in her mind of all the innocuous possibilities of Austin's absence, but no matter how many scenarios she crafts, the bottom line is that he's missing. Alexis tries to will him to appear, fashioning an image of his black and red bike helmet, shining through the heat-haze. The implication that Austin might have met a nasty end is within the realm of possibility. But then his body is found, and close to him are his beloved packets of Psych energy gels.

As an ER doctor, Alexis is trained to work backwards and move intellectually from effect to cause. As she looks out at the rice paddies and mountains in the distance, "a landscape as enigmatic as it was vast," Alexis tries to tries to convince herself once more that she's "worried for naught" and that Austin's death was just an accident. Back in her East Village apartment, Alexis looks at the autopsy photos, questioning the nasty black-and-blue wound on the back of Austin's hand.

Alexis knows how she had felt in Hoi An before she had learned Austin had lied. As she tries to navigate a maelstrom rich with confusion and grief, her mother says his death is a terrible thing and that it's not her responsibility to bring in a private investigator.

The trail leads the investigator--dark, weathered Ken Sarafian--into the orbit of Oscar Bolton and Douglas Webber, a champion darts player whose grand scheme is tied to the hardy descendants of Vietnamese rats. Nefarious Douglas becomes Alexis's nemesis. He wonders whether Austin had actually recruited Alexis for something. Alexis worked at the same hospital, and she's a physician. She also knows something about biology and chemistry. Austin was an excellent salesperson who knew about the extreme monetary value in rats.

As Alexis and Ken (and Quang, a detective back in Vietnam) hunt for clues, they descend ever further into the orbit of Douglas Webber. Bohjalian hints at the consequences if a grand pathogen should be unleashed and the ensuing political muddying and misjudged interference by free agents engaged in monetary reward, one that involves consorting with a rogue country. What if the pathogen is resistant to antibiotics? What if the rats that didn't die of the disease act as carriers? At first Ken can't quite grasp what Austin was up to. If he had to guess, he would conjecture that the first time he had gone to Vietnam, he'd visited the University of Hi Chi Minh City and met a scientist who is now dead.

Bohjalian threads the needle between rat-infested thriller and history lesson, delving deep into America's past involvement in the Vietnam War and the damage wrought by the bombings, napalm and Agent Orange. Riveting and poignant, the final propulsive chapters ultimately force Alexis into a reckoning with Webber while solving a murder that seems to have no solution.