What to read after Monster Planet?

Surviving the end of the world was the easy part? It's twelve years since the dead came back. Ravening, mindless zombies have devoured almost every living thing on the planet. The few, scattered survivors are surviving on canned goods and a refusal to give in and die. They are lead by Ayaan, a former child soldier turned brilliant strategist. She's twenty-eight years old, in a world where the average life expectancy is twenty-five. Together with her adopted ward Sarah, who has the psychic ability to see the life-force of the undead, she's gathered a few hundred survivors in Africa and given them safety, something to eat, and the possibility of a future. It would be a lot easier if the zombies weren't so well organized. Out of the east a dead prince has risen. The Tsarevich, the most powerful lich the world has yet seen, is able to command his fellow zombies and has crafted them into an unstoppable army. He has swept across Russia and eastern Europe, hunting down every survivor he can find. He's about to come down on Ayaan and her desert oasis like a tidal wave of death and horror. Yet quickly enough Ayaan realizes he's not just out for her destruction. He has something else in mind, a goal that will take him--and her--across oceans, all the way back to Colorado where the first zombies rose from the grave. He's going back to the Source and when he reaches it, no one will ever be safe again. The fate of all life on the planet is up for grabs, and if Ayaan and Sarah can't stop him there will be no more second chances?