In 1995, when AOL chat rooms are new and all the rage, 15-year-old Bostonian Katie McCann, a self-professed “book-obsessed dork,” finds a kindred online spirit in 19-year-old Dev, who’s “WmbleyLnDet” to Kat’s “KMcCann14.” Their shared passion is renowned mystery writer Carissa Miller, who created the witty and charming detective Adrian Lescher, basing him on noted criminologist Alik Lisser; Miller’s reputation has grown even more glamorous since her mysterious disappearance. Kat’s interest isn’t random. When she was 6, her mother, Barbara, was murdered, and Lisser was instrumental in proving that the crime was committed by her father, Bill, who was convicted and died in prison. Dev, who’s tracked down Lisser’s phone number and address, presses Kat to contact him. When Lisser schedules a speech at Harvard, Kat is convinced to try. Lisser, it turns out, is equally interested in her. At the end of their long meeting, Kat is convinced that he, not her father, killed Barbara. Many twists follow. In addition to encouraging nostalgia for the early days of online chat, before skepticism of other people’s identities and agendas became the norm, Corin also includes many references to mystery literature and film. The first-person narrative nicely captures Kat’s passion and youthful recklessness; the title is a warning to both Corin’s resourceful heroine and his readers.