So, who do we think it could be? We've got a few theories.
Noel Kahn. We know Ali has been working with Noel Kahn (Brant Daugherty), so the simplest explanation is that she's been sneaking out to give him his latest orders. But in Rosewood, the simplest answer is rarely the correct one, so we kind of doubt this is the full story.
Melissa Hastings. Melissa (Torrey DeVitto) is involved in all of this somehow, and Spencer did see Ali sneaking around by her house. Obviously, Ali lives nearby and could have just been cutting through the yard, but maybe she was there specifically to see Melissa. Perhaps the two are in cahoots — or perhaps Ali is trying to convince Melissa to keep an important secret.
Peter Hastings. Or maybe it's a different Hastings Ali has been seeing. We still don't trust Spencer's dad, and it's possible that he and Ali are working together, again perhaps because of a secret they both know about.
The man who is her "kidnapper." One theory we've seen around that we find intriguing is that Ali's fake "kidnapper" is actually someone she knew that "A" has turned against her, which might explain why she looked so shocked to see him. Ali has all sorts of "friends" whom she has somehow convinced to help her; it wouldn't be a surprise if some of them were strangers to the Liars.
The "A" team. Of course, we can't forget the theory that Ali really is Big "A". If that's the case, maybe she's been sneaking out to talk to her various minions.
With whom do you think Ali has been meeting? Let us know in the comments below!
Catch the next episode of Pretty Little Liars Season 5 on Tuesday, July 29, at 8 p.m. ET/PT on ABC Family.