In order to save his friend's life, Wyr sentinel Rune Ainissesthai made a bargain with Vampyre Queen Carling—without knowing what she would ask from him in return. But when Rune attempts to make good on his debt, he finds a woman on the edge. Recently, Carling's power has become erratic, forcing her followers to flee in fear. Despite the danger, Rune is drawn to the ailing Queen and decides to help her find a cure for the serpent's kiss—the vampyric disease that's killing her. With their desire for each other escalating just as quickly as Carling's instability spirals out of control, the sentinel and the Queen will have to rely on each other if they have any hope of surviving the serpent's kiss.