TV series · 2010–2017 · Developed by I. Marlene King · Starring Troian Bellisario, Ashley Benson, Lucy Hale
Four friends are tormented by an anonymous person who knows their secrets after their friend vanishes.
The series keeps the central mystery but expands it into seven seasons, with new plots and a different resolution.
Read the books for the original, shorter mystery. The series is a separate, longer story.
Pretty Little Liars by Sara Shepard
A fast, binge-able read that sets up a long series.
Who will like it: Readers who like teen mysteries and the TV series it inspired.