Carlos and Juan Alvarez de Santillanos y Menaya are the noble but impoverished sons of the father who scratched that message in the glass of a window in the family castle. The father went missing soon after, presumed dead. The brothers vow to seek him in the New World when they grow up.

Deborah Alcock (1835 – 1913) was a late-Victorian author of historical fiction. "She has long been known as the author of a series of admirable stories, the scenes of which are cast in stirring periods of religious history, and the religious tone of which is not only sane and true, but especially moving. The best of them is probably The Spanish Brothers.