Dr. Maya Summer works at Arizona Public Health, overseeing and researching a myriad of public health issues. A passionate advocate for a motorcycle helmet law, she also monitors disease-bearing mosquitoes, rabid bobcats, and the opioid epidemic—along with many other concerns. To maintain her clinical skills, she spends time at the nearby family medicine residency, seeing patients and teaching new physicians. Maya also navigates a complicated personal life: a somewhat troubled romantic relationship with a cardiologist; a retired physician-friend searching for new meaning; an undocumented neighbor raising a young son; and a cherished ailing old horse. A new danger looms when she sparks the anger of local biker gangs who want to stop her helmet campaign. As the intimidating warnings reach an unsettling highpoint, a past trauma that had been fueling her work now starts to haunt her—threatening to derail her carefully choreographed life.

Dr. Alex Reddish, a faculty member at the residency, enjoys Maya's company every week. He longs to know her better but also knows she is involved with a prominent cardiologist. A former shy chess champion, Alex has worked to remake himself into a more socially engaged person, though he cannot completely shed his reclusive past. His professional life is complicated by two resident physician advisees: a depressed and poorly performing man, and a seductive woman. And now someone seems determined to harm him. 

Maya and Alex turn accomplices when they try to unravel a spate of unusual illnesses afflicting residency staff, and discover disturbing trends. As Maya and Alex become closer, they must also tackle their personal pasts and individual demons, and find the courage to move forward.