Plot summary
Aria is sidelined by the flu and Meredith takes care of her while Byron is away. Mona and Toby plan their next "A" move against the Liars in the new "A" lair. Spencer takes a break from sleuthing to surprise Toby for their first anniversary. While fading in and out of consciousness, Aria is visited by Ali. Their brief conversation is ambiguous. When Aria comes to, she discovers that she is locked inside her bedroom. When Meredith checks on Aria, Aria realizes that Meredith has been drugging her to find a page from Ali's diary.
Aria makes her escape, but Meredith knocks Aria unconscious. Hanna arrives at her interview and finds it is a set-up by "A." When Hanna goes to the boutique, she sees in the window reflection a blonde girl wearing a red coat (the same color as Vivian's jacket) across the street, watching her. When Hanna turns around, Red Coat has disappeared. While making an escape, "A" haphazardly drops a key, which Hanna gives to Spencer. When Emily and Hanna go over to check on Aria, Meredith tricks them by locking them in the basement with an unconscious Aria.
Byron returns, appalled by what Meredith has done. Byron confesses his involvements with Alison to Aria. Aria believes him and burns the page from Ali's diary. Spencer tricks Toby and catches him in the black hoodie when he searches for the "A" key in Spencer's kitchen. Spencer is left heartbroken and confused.
Credits
Adapted from Wikipedia contributors, Pretty Little Liars season 3. HTML formatting and reference markers removed.