CJ is the oldest of the three Smithfork children. Sherry characterizes him as the responsible sibling—when their nanny leaves them alone, she places him in charge because she believes he can handle the responsibility of watching his siblings. However, despite his assumed responsible nature, CJ faces internal conflicts based on the responsibility placed upon him. Though he wants to find the treasure at the end of the clues, he first and foremost wants to keep his siblings safe but does not know how to do so without hurting their feelings. He particularly clashes with Patrick, whom he assumes cannot handle the same level of discourse he and Brid engage in because of Patrick’s age.

CJ acts as one of the three primary protagonists in the novel; Sherry encourages readers to root for him and his siblings as they traverse the physical landmarks of New York City and engage with the history behind those landmarks. However, he is a flawed protagonist. His mistakes place him in external conflicts, particularly with his parents. He lies and misleads his parents, his new friend at school, and his nanny to pursue the treasure. His lies catch up to him, and only when he reveals his deceits to his family—the same way they all expose the hidden map of New York City, which serves both symbolic and motific purposes in the novel—can he overcome the external conflicts between himself and his parents as well as the internal conflicts associated with his guilt over his lies and secrets.