"In the tower of Count Stelli in the ancient city-state of Agora, two children meet, apparently by chance. Mark has escaped the plague ravaging the city's slums. Lily is the servant who cares for him. At first, their only goal is survival: In Agora, everything can be bought and sold, debt is death, and Mark and Lily must barter their labor for their lives. Then comes an opportunity for them to exchange destinies: for Lily to escape the tower for the...

"Our heroes are back. Kind of. First, the bad news: an ancient evil - you know, your standard consume-all-life-in-the-galaxy deal - is about to be unleashed. The good news? Squad 312 is standing by to save the day. They've just got to take care of a few small distractions first. Like the clan of gremps who'd like to rearrange their favorite faces. And the cadre of illegit GIA agents with creepy flowers where their eyes used to be, who'll stop at nothing...

Uniting with Jason, Piper, and Leo after their dangerous quest, Percy, Hazel, and Frank wonder who will be chosen to fulfill the Prophecy of Seven, completing their group's number, and sail with them to an ancient land to find the mysterious Doors of Death.