Abandoned as a baby, Lydia is raised a Spartan princess; training alongside boys, in the Spartan tradition, she grows strong and is an expert rider and archer and talented inventor. Joining the army as a mounted archer, she competes in the Olympic Games, and forms an all-female squadron called the Myrmidons.

When the most powerful warrior in the world and recently crowned king of Macedon, Alexander, shows an interest in Lydia's elite squadron for his army, Lydia agrees to join on the condition that Sparta is safe from his empire-building ambitions.

Lydia rides to war in Persia with her Myrmidons and childhood friend, Lysander, by her side. However, through the bloody combat and sieges that follow, Lydia must face up to the fact it's not just battles she must manage. She can take on any foe; but what can Lydia do when confronted with intense and hopeless love?