When one of their tightly-knit group mysteriously disappears, four high school girls find their friendship difficult to maintain when they begin receiving taunting messages from someone who seems to know everything about their past and present secrets.

Struggling to return to normalcy after surviving Alison's attempt to kill them, Spencer, Aria, Emily and Hanna endure a series of disasters before realizing that they are being stalked by a new "A" who knows all of their secrets.

After surviving their latest encounter with A, high school seniors Aria, Emily, Spencer, and Hanna must try to convince the police that the real A is still on the loose, all while trying to stay alive.

The stalker's identity has finally been revealed but high school juniors Spencer, Emily, Hanna, and Aria seem condemned to repeat the past as they resume their unrepentant ways.

After high school juniors Spencer, Emily, Hanna, and Aria think they have seen Ali, their missing and presumed dead friend, they pursue clues from a mysterious stalker, trying to find out if she is still alive.

After their friend who has been missing for more than three years turns up dead, four former best friends continue to receive frightening messages from someone who knows damaging secrets about them.