The Pretty Little Liars craze has barely begun, and already the first season is celebrating its mid-season finale. ABC Family viewers were introduced to Aria (Lucy Hale), Spencer (Troian Bellisario), Hanna (Ashley Benson) and Emily (Shay Mitchell) only 10 weeks ago, but in that short time the series has become one of the most talked-about of the year.

Pretty Little Liars has been so successful, ABC Family has ordered 12 more Season 1 episodes…but Tuesday will mark the last new installment before the show breaks for the fall season. What can viewers expect? We’ve got a few of the gritty details…

The mysterious “A” continues to threaten the girls, and tensions escalate when the FBI arrives in Rosewood to delve deeper into the murder of Alison DiLaurentis (Sasha Pieterse). Lucy Hale (Aria) offered this hint: “Is there a level above shocking? That’s what it is.”

A new piece of evidence is discovered in the investigation, but the quartet of friends find themselves in the woods celebrating Mona’s birthday. Suddenly, a text from A: the mysterious villain may be at the party as well. Troian Bellisario (Spencer) dropped this bomb: “One of us knows who A is.” Egads!

Lucy Hale added, “and that girl is going to meet up with the other three, and then something crazy and unexpected happens.” On Pretty Little Liars, crazy and unexpected are par for the course.

The mid-season finale airs Tuesday on ABC Family at 8 p.m. Our best guess for the season-ending shocker? If one of the girls knows A’s identity…doesn’t she have to be eliminated?