Ailing Aria has reason to be afraid, while Spencer’s romantic gesture results in an unpleasant surprise.

The girls are reunited when they each begin receiving threatening messages from someone named "A," suggesting Alison is actually alive - and watching them.

After years of questions and mystery surrounding the night Alison DiLaurentis disappeared, The Liars finally learn what really happened to her that September night.

The girls are not feeling merry at Christmas because Spencer's murder charge looms over them. Things improve though after they see an opportunity to gather evidence to clear her name.

Who killed Toby's mother? Who hit Alison in the head with the rock the night she went missing? Who is Red Coat? Who killed Bethany? Who is the Black Widow? Why has "A" been targeting the PLLs all this time? After years of torture, Alison, Aria, Emily, Hanna and Spencer finally come face-to-face with their tormentor and learn the story of how and why Charles became "A."

All is revealed as the ultimate endgame comes to light.