This book is the story of Malencia Vale and her quest to become a candidate in "The Testing", a series of tests to determine whether graduating high school students have what it takes to go to the University.
When the book begins, we learn Cia is graduating and wants more than anything to go to University to make her parents and brothers proud. She learns she has been accepted through Michal Gallen, a Tosu City (where the University is located) official. He escorts Cia, Tomas (Cia's friend and crush), Zandria (another girl who is very artsy and always flirts with Tomas, and two other students to the city to begin testing.
Before she leaves home, Cia's father tells her to be very careful because even though he can't remember what happened, he knows the officials erased his memory of the testing but he gets brief glimpses occasionally and knows it is bad, although he does say it might just be nightmares and not memories.
The first test begins with the students doing written exams, after which Cia's roommate, Ryme, kills herself by hanging bc she can't stand the pressure. All the officials seem unconcerned and Cia realizes something is wrong with their situation and that they are all in danger if a death is treated so nonchalantly.
The second test places boxes in front of the students and they have to complete several tasks, one of which being sorting plants that are poisonous from those that are not. The testers then make them eat the plants which they sorted as safe, making Cia realize this is what was meant by being "penalized" for a wrong answer. With the next box they have to fix a non-working radio, and when a candidate pulls the wrong wire a nail shoots him in the eye and kills him. Once again, the officials tell them to continue with their work and do nothing to help. By this point, Cia is beginning to hate the officials but can't do anything about it for fear they will kill her also.
The 3rd test is the biggie. They are told they can pick 3 items from a room, and that they will be dropped off in the desert and must come up with a way to get back to the testing facility (supposedly showing their strengths and whether they can survive in the demolished outlands). Cia picks a gun, a medical kit, and some canteens for water. She and Tomas set up a plan to meet at a large building once they figure out they are going to be dropped off in Chicago due to the way the map looks (I think it's about 400 miles they are going to have to travel?).
Michal is Cia's escort again, and she realizes he is on her side and against the whole "Testing" process when they make their last stop before the drop off to have lunch and he takes her away from the cameras to give her pointers on surviving.
She wakes up near Chicago in a tube-type seating area and goes to find Tomas. On her way she is attacked by another candidate with a crossbow but manages to escape, almost falling off a crumbling bridge, but Tomas catches her and they begin their journey.
The first major milestone is finding an "oasis" when they are dying of thirst, but Cia thinks it may be booby trapped and she is right. While she goes across a large hill to see if there is water anywhere else, Tomas can't wait any longer and when he goes to get a drink from the oasis it blows up and pokes a huge stick through his upper leg. Cia mends him and they continue.
They next come to a maze of roads and have to keep backtracking to try to find their way out. Will, one of their friends they made while coming to the testing (along with his brother Gill, who was "sent home" but probably killed), finds them and joins up with them. When they are beginning to run out of food Cia goes to hunt and comes into contact with mutant humans living in the wild and is forced to kill them when they attack. When she makes it back she sees that both Will and Tomas's eyes are haunted and they are hiding something but they won't tell her what it is.
Cia and Tomas eventually leave Will behind since he doesn't have a fast mode of transport and they need to hurry (they made homemade bicycles to travel faster). Farther down the line, Cia comes into contact with a man from over the fenceline who keeps giving her food and eventually tells her he is there to help bring down the testing officials, and there are "many more, even inside the city" who want to help. He gives her a serum to take to prevent her from succumbing to the truth serum officials give after this test to learn everything they can about a candidates thoughts.
They begin to pass through another city, and one of their testing friends, Brick, begins to rain down machine gun fire on the mutant humans following them. Cia yells for him to stop but he can't hear her and kills them all. This really hurts Cia because these mutant humans were people too and werent doing anything to harm them, just following them curiously. Cia feels responsible because she saved Bricks life back at the testing center by telling him one of their teammates (Roman) had set them up for failure during a test involving team problem solving where they were supposed to split up the questions and then go in a room and answer them one by one. If a door had been opened, once it was opened again (tampering with teammates answers) it would explode. Roman goes in and answers all the questions so that the doors will explode for all his team after him. Cia figures it out and tells Brick, so she feels him killing the mutants to "pay her back for saving him" is her fault.
While they are camping, Roman comes along and tries to kill them, but Will shoots and kills Roman first. He has found a skimmer (a type of hovercar) and has caught up to them.
When they finally get near to the end of the test, Will tries to shoot Tomas and Cia and reveals his true colors, but Cia fires on him and he runs away, but not before shooting Tomas.
Cia manages to get them across the finish line and they are taken back to the testing center for the 4th and final test, which is for them to tell the officials their experiences with the truth serum. Cia takes the vial and is able to not tell the officials about her father's warnings about the test because she is afraid that he will be killed since he has memories left of the testing. She asks Dr. Barnes about how Zandri died (she knows she died since she didn't return to the testing center), and Dr. Barnes laughs and tells her she should know since Zandri's bracelet is in her bag. Cia realizes this is what was haunting Tomas and begins to wonder if Tomas killed Zandri since she saw blood on his knife.
Cia is escorted back to her dorm room, and she begins to hide in the bathroom where are there no cameras to see her cry for fear they will think her weak. She accidentally pushes a button on her brother's TransCommunicator that she brought with her (a type of walkie talkie, compass, recorder), and his voice starts playing. She decides to record her own experience in case they take her memory of the testing away. She finds out that she passed the testing, feels a pinch on her neck, everything goes black and time skips forward to 6 months down the road at the university. Cia's memory has been wiped but Michal gives her a gift box (it's her birthday) and tells her it's a gift from home, but Cia gets the meaning and waits til she is alone to open it. It is the TransCommunicator, and she pushes the button on the back to hear what the recording is, and the book ends with her listening to the recording in disbelief.
Note: There was not a good place to put it in the summary, but for reference in case it comes up in the next book, the officials made all the testing candidates wear bracelets with symbols on them to sort their group, which Cia figures out are recorders and that the officials are listening to them during all their tests.