Captive Scorpio — Alan Burt Akers

Dray Prescot, Earthman of Kregen, that wonderful world circling the twin suns of Antares, had risen high in the empire of Vallia, but luck could not always sustain him. When, at last, all the forces opposed to his lands, his princess, his emperor, and to him personally, converged, it was to produce the darkest hour of his long career. For treason struck at the court, while rebel armies marched from the backlands, the war fleets of enemy nations were aloft, and the uncanny wizardry of a master scientist launched a spell of doom for all Prescot held dear. With his back to the wall, Dray Prescot faced that time of peril with unflinching will... until the cruelest blow of all was struck: his warrior daughter Dayra rode in the vanguard of his foes!