What tone did Ally carter set in the beginning of the text for only the good spy young

In Chapter 1, while ice skating in London, England with her best friend (and fellow trainee spy) Rebecca, narrator Cammie has a surprise encounter with very attractive (and fellow trainee spy) Zach. Their flirtatious conversation reveals that Zach is looking for one of Cammie's teachers and another fellow spy, Joe Solomon, who has missed several appointments for making contact. There is a tone of mystery, excitement, and adolescent expectation.