Having just accomplished her last mission, Kara learns that the evil Seirs are slaughtering Sensitives that refuse to swear an allegiance to Lilith—the Netherworld's princess and her diabolical half-sister. While on assignment, Kara discovers that Lilith is searching for an ancient weapon that can destroy mankind.

The Seirs' army grows with every Sensitive they recruit— the odds of victory are grim. With the help of her friends, Kara finds herself on another dangerous mission entrusted to her. But can Kara find the weapon before Lilith annihilates the entire human race?