What made Spencer Hastings disappear? That's the question on everyone's mind in the March 5 episode of ABC Family's Pretty Little Liars.

Upon seeing Toby Cavanaugh's dead body in the woods during the Feb. 26 episode, Spencer (Troian Bellisario) suffered an emotional breakdown and was discovered by park rangers, who transported her to a local mental institution. Because she had no identification, she was admitted anonymously.

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The following day, Melissa Hastings (Torrey DeVitto) visits Rosewood High School to inquire about her sister's whereabouts. "Have you seen Spencer?" she asks Aria Montgomery (Lucy Hale), Hanna Marin (Ashley Benson) and Emily Fields (Shay Mitchell). "Have you talked to her?"

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Melissa continues, "Spencer didn't come home last night. She's not answering her phone. I was hoping she was here with you, which is why I came here before I went to the police."

Vice Principal Arthur Hackett (John O'Brien) then asks the girls to come forward with any information they have regarding Spencer's location. "I understand Spencer's been a little distracted lately. Is there something on her mind that she shared with you?" he asks. "Anything about her plans?"

Afraid of what telling the truth might mean for Spencer, a wide-eyed Emily replies, "No, Mr. Hackett. She hasn't said anything to us."

Pretty Little Liars airs Tuesdays at 8 p.m. EST on ABC Family. Watch the sneak peek now.

This article originally appeared on Usmagazine.com: Pretty Little Liars: Spencer Goes Missing After Toby's Death