A Novel of the Days of Prince Henry, the Navigator"" extends Slaughter's range to still another period and along with some active seafaring and its attendant adventures, there is also extensive research. Andrea Bianco (an actual figure) who for eight years- while officially declared dead- was the slave of the Moors, is freed and brought back to Venice by Dom Bartholomeu, and his daughter Leonor. There his half brother, who had married his fiances, Angelita, charges him falsely so that he is again sentenced to slavery- this time under Prince Henry of Portugal. To the Prince he can prove that he is the mapmaker, and with his new (old) instrument of navigation heads voyages of exploration to Africa, the Antilles and the Azores. He falls in love with Leonor- but cannot altogether forget Angelita- until his return when he realizes her complicity in his step-brother's murderous intentions....As one might expect- the characterization is two-toned; as one might not expect, the scenes of seduction, far fewer, fade out in the larger display of navigational knowledge and physical prowess. You can still take your bearings from the earlier historicals.