Nancy Drew finds a mystery when she discovers an email sent to a competing law firm from her father's office computer. Several of her father's clients have been closing cases early in a panic. Nancy suspects the email is related and investigates the office employees, including Blaine Warner, Henry Yang, and Bryon Thomas. During a stakeout at the office with her friend Bess, Nancy and Henry discover that Henry was also trying to solve the mystery. They break into Blaine's computer and find she sent the emails, attempting to steal clients. Blaine is arrested after knocking out Bess and Henry, and Nancy solves the case of the mysterious email.