Title: El círculo negro
Subjects: Family secrets, Families, Brothers and sisters, Hermanos, Huerfanos, Wills, Fiction, Novela juvenil, Code and cipher stories, Familia, Secretos de la familia, Orphans, Juvenile fiction, Genealog̕a, Genealogy, Cryptography, Familias, Historia, Ficción juvenil, Criptograf̕a, History, Mystery and detective stories