Paige throws Emily a surprise birthday party with even more surprising guests -- Jenna and Shana.
Aria relies on Jake to help her understand Mike's new attitude.
Caleb and Toby team up to investigate "A" and what really happened the night of the lodge fire.
Toby and Spencer visit Ravenswood -- which is unlike any place they've ever seen.
Spencer and Emily make plans to visit a nearby college, but they have very different agendas.
Toby finds a new source of information into his mother's death, but it only leads to more questions.
A clue in Ali's things leads the Liars to a creepy mask maker.
The presence of Mrs. DiLaurentis in Rosewood continues to unnerve all those around her.
In the season four premiere, the girls turn to Mona for answers.
A special episode encompassing the first three seasons of Pretty Little Liars.