By Jessica Derschowitz
Updated October 26, 2015 at 01:28 AM EDT

Scream Queens is nearing the end of filming for the show’s first season, but even as they go into this final stretch, the stars are still in the dark on how it’s going to end.

Keke Palmer, Emma Roberts, and Lea Michele spoke to EW’s Tim Stack on Saturday at the first-ever EW Fest in New York, and revealed that they still haven’t received a crucial part of one of the scripts.

“We actually just got episode 13 and the last act is missing … they don’t want us to know.” Roberts said. “So I think we’ll be left until the last couple of days to find out who the killer is and why and what the setup’s gonna be for next year.

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Scream Queens creator Ryan Murphy also said at EW Fest that the killer’s identity will be revealed in the final episode — “we spent a lot of time taking the audience through how the killer got away with what they got away with,” he teased, “so lots of flashbacks, lots of twists and turns” — but with just an episode and a half left to shoot, do the Kappa sisters know who the culprit is?

“We have so many theories,” Palmer said. “There’s a couple that I’m pretty sure about, but we can’t tell you guys!”

Watch Palmer, Roberts, and Michele discuss Scream Queens in the video above, and head here for more from EW Fest’s Ryan Murphy & Friends panel.