Cross my heart and hope to spy
Ally Carter
 When Cammie returns to school, she and the other girls are frustrated because the East Wing is off-limits. Fumes from the chemistry lab have supposedly contaminated the area making the girls have to walk around the wing adding ten minutes to their walk back to their rooms. The next day on a CoveOps mission at the National Mall the class must get to the ruby slippers exhibit by five o'clock practicing counter-surveillance. Only one girl in the class succeeds in the mission. Cammie fails when Zach, whom Cammie believes to be a teenage boy, follows her from the elevator. After the failed mission fifteen boys, Zach being one of them, and their teacher Dr. Steve from the Blackthorne Institute, come to the Gallagher Academy and they take up residence in the East Wing. Cammie meets Josh again during an exercise in Roseville, VA and finds out that he is dating DeeDee. For Cammie the incident confirms her mother gave Josh the special memory wiping tea. During a CoveOps/Culture and Assimilation cumulative exam Cammie and Zach dance together. Cammie has a slight wardrobe malfunction and she tries to leave via a passageway where Zach is waiting. A Code Black occurs,meaning the school's secret is in danger of being released,and Cammie gets blamed when Zach mysteriously disappears. Cammie, Liz, Bex, and Macey decide to investigate the Blackthorne boys, but the covert listening devices in the boys rooms, and the tracking systems/trackers in their shoes, don't give them any information. Then Cammie goes on a study date with Zach. On a Saturday trip into Roseville, Cammie and Zach are walking around town together, and Zach tries to kiss Cammie while knowing that Josh and DeeDee were watching. Cammie suddenly becomes aware of this and seeing that she hurt Josh, doesn't let Zach kiss her. On the same trip, the Gallagher girls have to come back early when Zach lies about seeing a trailer before. The girls arrive at the mansion to a massive security breach – a disk containing the information about all the alumni of the Gallagher Academy has been stolen. Using a secret passage, the girls get out of the mansion and follow trackers that Bex and Liz planted on the Blackthorne boys. Macey comes across them outside in a Gallagher Academy van she "commandeered" and they follow the tracking devices. They meet up with the boys outside an abandoned manufacturing plant owned by the school. Zach convinces Cammie that he and the boys are innocent and they team up to get the alumni disk back from Dr. Steve, who stole it. They succeed in stopping Dr Steve from getting away when Bex puts him in a choke hold, and it is revealed that the recovery of the disk was a test to see if the girls could accomplish the mission with the boys. At the end the Blackthorne boys have to leave and Zach kisses Cammie telling her "I always finish what I start" referring to the Saturday trip to Roseville.