While planning a surprise one-year anniversary dinner, Spencer discovers the truth about Toby and confronts him. Hanna has a run-in with someone in a black hoodie while on what she thought was an internship interview. Meanwhile, Paige and Caleb team up to take down Mona. Meredith drugs Aria while searching for the pages from Ali's diary. When Aria wakes up, she discovers what Meredith has done, but before she can call for help, Meredith knocks her out and locks her in the basement. Hanna and Emily try to save her, but they end up locked in the basement as well. Thankfully, Byron comes to their rescue. He tells the girls what happened the night Alison went missing. Aria burns the pages of Ali's diary and tells her father she believes him.
