Pigeon fancier Ruben Nilsson finds the strange bird of the title and takes it into his dovecote, unleashing a pandemic that threatens inhabitants of the Swedish island province of Gotland.

As the ailing Ruben is spreading the mysterious disease to his friends and neighbors, police discover the body of a murdered man on an abandoned farm. The victim is a foreigner with no identity papers. An empty birdcage in the victim's car is the first clue to the source of the killing flu.

Detective Inspector Maria Wern, the single mother of two children, is assigned the murder case. The investigation is barely begun when her young son falls ill at soccer camp and is quarantined with other children and adults. Author Anna Jansson here skillfully portrays the very human reaction of a woman coping with the twin difficulties of a demanding job and the welfare of her children.

Since this is both a mystery and a medical thriller, the two are connected. The mystery aspect is suspenseful enough to keep a reader turning pages, but the medical emergency and the reaction of personnel and the community is the stronger part of the story. The most frightening consideration is that a medical emergency of this kind can happen. Jansson is a nurse, which lends authenticity to the story.

This is the first in the Maria Wern series available in English. There were places where I found the translation a bit wooden. Still, if you like Nordic noir, I'd recommended giving this series a look.