From the preview:
In Unseen Forces, the upcoming first expansion for Elder Sign, investigators old and new return to the museum to complete adventures in an attempt to keep the Ancient Ones from awakening. Mysterious forces are at work, as horrifying new monsters and dangerous new Mythos cards collude to unleash ruin on the investigators. As they venture through the museum, investigators may find themselves blessed as they work to finish tasks and complete adventures. Good fortune may not last long; a curse may be waiting just around the next corner.