The Isabella and Ferdinand Trilogy, book 1: Castile for Isabella
Jean Plaidy1960

With fifteen-century Spain rent with intrigue and threatened by civil war, Isabella became the pawn of her ambitious, half-crazed mother and a virtual prisoner at the licentious court of her half-brother, Henry IV. Was she, at sixteen, fated to be the victim of the Queen's revenge, the Archbishop's ambition and the lust of Don Pedro Giron, one of the most notorious lechers in Castile? Numbed with grief and fear, Isabella yet remained steadfast in her determination to marry Ferdinand, the handsome young Prince of Aragon, her only true betrothed.