Defenders of the Faith by Jean Plaidy

This is a powerful story of the troubleous days when Tudor succession was in dispute. The chief characters are two contrasting cousins - one daring, brave and adventurous; the other quiet, reserved and thoughtful. But each has his own kind of courage. It is set in Chelsea, Kent, and Spain, and is a vivid portrayal of a family which came to know the wrath of the Spanish Inquisition.