Pretty Littles Liars is finally back with a bang! Besides wondering what will happen to Hanna, the big question is who are the Liars burying in the premiere? At this point it could be anyone. The obvious choice would be Hanna. She's already in the clutches of A. D. and if the other Liars don't find Charlotte's killer in the next 24 hours it's over for Hanna.
But why would the Liars secretly bury Hanna? She's their friend and it's not like Hanna would've died at their hands so it's unlikely it's really Hanna they bury. Whoever the Liars are burying it's probably someone they kill by accident. Hopefully it's Elliot.
Elliot has been sketchy since the moment he showed up on this show. Although we all know he's evil now, the Liars are still one step behind but with Alison getting more restless in the hospital it's possible that she's figured out the truth about Elliot but by keeping her "crazy" Elliot is also keeping her quiet. Maybe Emily confronts Elliot and things get violent and she accidentally kills him. Or all the Liars confront him and they're all responsible for how he dies. Either way there's a good chance it's Elliot they're putting in the ground and honestly it'd be good riddances.
If it's not Elliot another option is Mary Drake. The Liars already don't trust her (and with good reason). It wouldn't be crazy for them to confront her and for things to go south. With Mary Drake intent on getting revenge for Charlotte and the Liars intent on saving Hanna at all costs emotions would be running high. Maybe Mary Drake threatens the Liars and they fight back. Or they planned to ambush her and make her tell them the truth but their plan goes wrong. Who knows how it happens but it would make sense for Mary Drake to be the one in the grave. She's the obvious villain right now and often in Pretty Little Liars the obvious villains are just a stepping stone to finding the real one.
Whoever's in that grave it's clearly someone the Liars didn't mean to kill. If it's not a villain then it may be someone they're kind of close to, which would be even worse. In any case, the Liars may have gotten themselves into even more trouble than they're already in.