What episode in season 3 do they find out Alison is alive in Pretty Little Liars?

In Season 3 of Pretty Little Liars, the revelation that Alison DiLaurentis is alive occurs in the episode titled "A DAngerous GAme," which is the 24th episode of the season. The Liars discover this shocking truth during the season finale, setting the stage for further twists in the storyline. This moment significantly impacts the dynamics among the characters and the overarching mystery of the series.