Credit: Video Still

This promo for Pretty Little Liars Season 3, Episode 5: “That Girl is Poison” (airing August 21) from Canada's MuchMusic leaves us with chills.

In it, we see that Spencer (Troian Bellisario) thinks Paige (Lindsey Shaw) is involved with "A". But is she right? The stakes are higher than ever when the girls are faced with life-threatening situations, so any wrong assumption could lead to disaster...

Check it out below.

Credit: MuchMusic via Youtube Photo: Pretty Little Liars Season 3, Episode 11 Preview: Is Paige "A"? (VIDEO)

Catch an all-new episode of PLL on Tuesday, August 21 at 8 p.m. ET/PT on ABC Family.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaMartin47.

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