The Whitby Library has been a busy place lately, between book clubs, children's storytimes, and students working on research projects. Ann has been busy, too, which is why she's so glad to see some new volunteers to help the staff out. One of the volunteers is worried, though, and comes to Ann with a problem. She's seen something odd . . . maybe even suspicious. Ann tries advising her, but the volunteer still seems troubled. The next day, the woman meets her own suspicious end. Can Ann, with the help of her friends, help solve the mystery before someone else is permanently checked out?