Seventeen year old Ruby Behl never expected to be thrust into a position of power. But so much has changed in the past few months, she's prepared to accept the responsibility. Her best friend Wesley was Marked with the Tercera virus. Her boyfriend Sam was shot to death. She found her father's journal with the key to a cure. But the leaders of the port cities have assembled with a threat of their own: to Cleanse the world of the remaining Marked. When a vicious attack accelerates the virus, Ruby and her friends have less than a week to find the cure, prevent the Cleanse, and rescue her aunt from execution. Ruby is convinced her father's old partner stole the antidote, but she has no clue to his identity. Torn between saving her family or hundreds of thousands of Marked, she must figure out who he is and find him before time runs out-for everyone.