When Emma's city's forcefield is hacked and her city is destroyed by invading machines, she is forced to live in a world outside of her pretected city. She finds an old cave and this is her new home for two years. She also hunts with her one of only possesions from her old home-- a spear
Two years after what Emma calls the City Takeover, Emma stumbles upon an underground city full of refugees. They tell her that they are surprised to see her because they thought everyone from Tyra City ( her home city) was killed or taken by the machines. They also told her that the robots aren't trying to kill people( unless they have to), but trying to turn them into robot soldiers. Emma says she will help them if she is allowed to stay here. They agree.
Emma trains hard and long for two weeks so she can get sent on missions. The purpouse of the missions is, since the refugees can't destroy the machines yet, they destroy them little by little with each mission, targetting thier factories and power plants. Emma wants to get revenge on the machines, so she wants to join the DTM squad, or the people who go on the missions.
Emma is finally sent on her first mission. She is sent with a boy named Ryan, who is her official partner, to destroy a machine factory. But in a one-on-one fight between her and a machine soldier, she is captured by the machines and taken to thier base.
The book ends where Emma is knocked out and is slowly closing her eyes as she is being carried away by a machine.