Who’s missing? Well, we haven’t seen Melissa in a while. Jenna hasn’t been seen since the Christmas episode. And, Paige hasn’t been seen or heard from since she allegedly moved to California. Based on Rosewood’s history, it would make sense that one of these three girls would be found in the infamous barrel that we’ve all grown to hate because no one will tell us what’s in it! If you stop to look at the facts, it would make perfect sense that one of these girls would be found in the barrel.
Fact: As far as we know, no one has seen or heard from Melissa since she left that video confession for Spencer to watch. Theory: “A” killed Melissa, because she is Spencer’s sister and “A” knows that, even though they always fight, Spencer does love Melissa. Tanner made it a point to tell Toby that he couldn’t tell anyone what is in the barrel. That would be why he “blew off” Spencer at the end of the last episode because he knows he can’t look at her or talk to her without telling her that Melissa was the one in the barrel.
Fact: Jenna has been mysteriously missing since the Christmas episode and prior to that she was as much of a prominent character as she has usually been. Theory: Knowing that Toby knows more about of the “mysterious” events and murders that have happened in Rosewood than any of the other police, “A” decided to find a way to distract him from his work. Thus, (s)he murdered Jenna, stuffed her in the barrel, and tipped off the liars, knowing that Toby would find out. The hateful part of Toby’s love-hate relationship with Jenna may normally be stronger than the love part, but they are still step-siblings, and Toby always seems to have a soft spot in his heart for Jenna. That would also explain why he’s avoiding Spencer. Not only is their relationship a little rocky right now, but he is also feeling emotional about Jenna and doesn’t want to talk to Spencer about it because 1) he doesn’t know how he feels 2) Spencer and Jenna always had a very complicated relationship.
Fact: Emily hasn’t been able to get a hold of Paige since she moved to California. Paige’s move to California seemed very abrupt and random. Theory: Because Paige is about as connected to “A” as any of the Liars’ significant others, “A” didn’t want her to leave Rosewood, because if she did, then the other girls might get the idea that it’s okay for them to leave as well. Of course, if any of the girls left Rosewood, then “A” wouldn’t be able to continue his/her game and that would make “A” very upset. Thus, once the Liars’ find out that it’s Paige in the barrel, “A” will send them a message saying, “No one leaves Rosewood unless I say so. – A”
General Theory: If any of these girls is in the barrel, then it would be because we’re getting down to the boiling point of finding out who “A” is and the writers are starting to eliminate as many suspects as possible, so that it will become easier for us to decipher who “A” really is.