A series of kidnappings of little girls and a group of threatening letters convince Johanna Hamilton that her daughter, Kirsten, may be the next victim
Picked up the paperback for a quarter at the flea market. Holy 80s super cheese. Also, 'um-hum' being used in dialog at least a hundred times.
(For the record: I'm pretty sure the Samantha Chase who wrote this book isn't the Samantha Chase listed on Goodreads as the author. That author's bio says her first book was published in 2011. This book was published in 1988.)