Aria, Emily and Hanna search for Spencer, unsure if she went off on her own or if "A" is behind her disappearance, and their concern grows when they discover Spencer's family has no idea where she is. Meanwhile, Emily meets Olympian Missy Franklin.

In the third-season finale, Spencer returns home and claims she's fine, but her friends have doubts about whether she's fully recovered. Meanwhile, surprising revelations surface.