Characterization in a Shellabarger novel, especially in Captain from Castile, is superficial and secondary to plot and action.

Pedro de Vargas is an eminently likable young man who gets by through quick thinking and a deft hand. He moves through a fast succession of scenes — from imprisonment in the dungeons of the Inquisition to the invasion and conquest of Mexico to intrigues in the court of Emperor Charles V — leaving him little time to reflect on the consequences of his actions. Manly and noble, Pedro is also ingenuous, unlike later Shellabarger heroes.

Catana Perez, the heroine, is more spirited, practical, and worldly than the virtuous heroines of the later novels, but she is as much a stock character as they are. Beneath her rough exterior beats a heart of gold. The villains, arrant scoundrels all, come perilously close to being little more than comic strip bad...