Abandoned by his father to drown off the coast of Spain, Tristram Pascoe's life is saved by Sara, who is in a marriage of convenience to a Portuguese nobleman. Suspected of heresy, Sara is brought before the Grand Inquisitor and risks being burnt as a witch to help Tristram escape. Tristram is pressed into service as an English spy, and travels to Cadiz and Lisbon, where the Spanish invasion force is assembling. From the first rumors of a Spanish invasion to the horrors of the Channel firefights, "Armada" is a story of the triumph of human love over religious conflict.