Four estranged friends are brought back together after each begins to receive frightening letters from a person they suspect is a long-missing associate.

Relationships are explored among the girls as they pay tribute to Alison's memory; Aria encounters her father's former mistress.

The girls take matters into their own hands and try to put a stop to "A," but the girls' problems are far from over.

The girls pay the price for trying to ignore "A"; a new male arrival changes the status quo; Spencer's father asks her to throw a tennis match.

Disturbing secrets threaten to ruin the girls' homecoming dance; an odd date choice leads to a sticky situation.