Borrelia is the second novel featuring Maya Maguire, medical detective, in her journey as an Asian American veterinarian solving microbial mysteries. A pregnant New Mexico woman is dying from relapsing fever and reaction to her treatment for infection with Borrelia, a squiggly spirochete bacteria. After searching for blood-sucking ticks at the patient's cabin, veterinarian Maya Maguire of the Centers for Disease Control and Prevention has a car accident which upends the confidence gained during her first year of CDC training. Her childhood panic disorder and struggles with its treatment block Maya's dreams of achieving balance between demands of public health and her almost-fiancé, a physician incapacitated by Arizona anthrax. Summer heatwaves spike lice-associated Borrelia in Europe. Maya consults on a surge of deaths in Borrelia-infected refugees relocated to Norway. When extending her mission to Portugal and Morocco, impacts from her fieldwork pile up. At home, she juggles support for a harassed friend and a colleague rejected by his biological family, while mentoring a trainee stepping over the line. Protecting those she loves backfires when she hides her own legal jeopardy. Maya successfully battles Borrelia until swept up in an Atlanta protest march. Juggling difficult choices of disclosure versus service threaten to overwhelm, until recovery of a loved one and decisions about the future allow her to take important steps forward.