Even though the disappearance of Alison DiLaurentis has been solved, Spencer, Emily, Hanna, and Aria harbor other secrets which could interfere with their perfect lives, as they try to forget what happened to them in Jamaica last spring.

Hanna, Spencer, Emily and Aria are trying to move on and forget about their old friend Alison DiLaurentis and all the torture she put them through, but someone is trying to keep her spirit alive.

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.

Best friends Spencer, Aria, Emily, and Hanna find themselves under suspicion when the mysterious stranger named A tries to blame one of the girls for the death of their friend Alison and threatens to reveal the girls' darkest secrets.