Paraphrased from Sampson's summary at the beginning of Episode 5.
The party arrived at the ruins of Kamathan, did a little dungeon crawl. They found a dehydrator, a room that gave objects google-eyes and a room that gave another plot thread to eventually figure out. After the dungeon crawl, ChaCha at one point got her hand stuck on a crystal. They eventually came to a room with two dead bodies. One of them being Mewin who they were supposed to find. With her was another dead body, that as far as they could tell at the moment, she killed. That body had a plot point - a badge that only Atalia recognized.