Finding Cassie Crazy (titled The Year of Secret Assignments outside of Australia and the UK) is a novel by Jaclyn Moriarty. It was first published 2003 in Australia. The novel is both a stand-alone and also the second book of the Ashbury/Brookfield series.
Plot
The novel follows the correspondence between students from two rival schools. Cassie Aganovic, Emily Thompson and Lydia Jaackson-Oberman, attend the prestigious, private Ashbury High; Matthew Dunlop, Charlie Taylor, and Sebastian Mantegna ("Seb") attend the public and notoriously rough, Brookfield High. In a special pen-pal program between the schools (previously seen in Feeling Sorry for Celia and set up by Mr. Botherit), Cassie begins to write to Matthew; Emily writes to Charlie; and Lydia exchanges letters with Seb. The letters are initially different degrees of hostile. Emily and Charlie poke fun at each other's writing, while Lydia and Seb bicker about whether or not they can trust each other. Matthew however, is much worse. He continuously threatens Cassie (i.e. "I'll break your fingers one by one"), but she responds calmly and tells no one of the abusive letters. Over time, the letters change tones. Charlie and Emily go on "practice dates" to help Charlie date the girl of his dreams, Christina Kratovac (who was the Brookfielder Elizabeth Clarry wrote to in Feeling Sorry For Celia). Lydia and Seb participate in "Secret Assignments" that eventually lead to their forming a close relationship. Cassie and Matthew begin to go down a similar path and plan a meeting after Cassie finally starts getting civil responses from Matthew. However, his sudden kindness is a ploy. He stands her up and then, on a following meeting, proceeds to rip up a letter that she had sent and openly mock her. This is especially hard for Cassie, because her father had recently died of cancer and Cassie had not yet come to terms with his death. This is why she never reported Matthew's initial abusive letters, she had not been feeling like herself and had lost her confidence.
When Lydia and Emily find out what Matthew has done, they ask for help from Seb and Charlie to get Matthew back. They soon discover that Matthew is not a real person. They are forced to hatch numerous plots to find who Matthew really is, or if he even exists. By the clever use of glitter in a letter, they discover that Matthew Dunlop's true identity is Paul Wilson, the form captain and star of the school drama club. He is also, coincidentally, the boyfriend of the girl Charlie likes, Christina. The five (Emily, Charlie, Lydia, Seb and an initially reluctant Cassie) work together for revenge. Seb beats Paul up after Paul humorously tells him the story of his deception. Seb is set to be going to an art show the very next morning, and Paul threatens to tell the principal in an attempt to penalize Seb. But just when this is about to happen, Lydia, Emily and Cassie pretend to be casting agents and call Paul, telling him he has a job and needs to come to a certain time and location to get his makeup done (Paul is an aspiring actor) and practice lines for a last-minute filming rehearsal. The girls' prank is successfully pulled off and Paul realizes at the end that it was all an elaborate plan to stop him from telling the school principal. During all this time Emily and Charlie seem to show signs that they like each other. Meanwhile, Lydia and Sebastian kiss on a secret assignment.