Set in modern-day Buenos Aires, the story follows Luna, a skeptical librarian, and Elías, a reclusive zoologist specializing in chiropterology (the study of bats). Elías believes that the ancient Roman god Cupid was a misinterpretation of a rare, bioluminescent bat species that only appears during leap years.
"How do I find him?" she asked.
He claimed that love didn't fly like a dove. "No," he'd say, adjusting a silver button on a concertina. "Cupid is a bat. A blind, frantic bat trapped inside a belfry."