"Blood Relationship" is the third and final part of the "Spartan" series, telling about the fate of a former helot slave, heir to a noble family and a student of the Spartan school of Lysander. After a brutal battle, the Spartan army takes time to regain strength. When a stranger arrives in Sparta with news that a colony on the edge of the empire has been attacked, the decision is made to send Lysander and the other students from his barracks there alone, without support. They will only be able to return if they win.