For as long as anyone can remember, there have been two Earths. Two versions of every city, every building, even every person. But the people from the second Earth know something their originals do not: two versions of the same thing cannot exist. For the people born on the second Earth to survive, they must kill their originals and take their places. Lirael had one purpose from the moment she was sent to Earth 1 as a child--to learn everything she could about her other self. When the time comes, she kills her original and slips seamlessly into her life. But as Lirael takes over her original's life, she begins to wonder if there's more. More than mindlessly following orders, more than living life in a holding pattern, waiting for a war that will destroy everything and everyone she has come to love.