The RecordistWalter and Astrid use the makeshift laser to recover another tape from the ambered part of the lab. The contents point to a location in northwest Pennsylvania, though the instructions for what to do there are garbled. While Astrid stays behind to try to improve the tape's playback, Walter, Peter, Olivia, and Etta travel to the designated location. There, they find a small camp of human outcasts, all displaying splotches of bark-like material over their bodies. They are introduced to Edwin, the camp's leader, who explains that their condition is due to some unknown agent within the area. Those in the group consider themselves to be recorders of history ever since the takeover by the Observers in order to prevent history from being rewritten by the Observers. They maintain a large number of data cubes containing whatever knowledge they can recover, including much about Fringe division. Edwin is unable to find information about Walter's previous visit to the site, but Astrid is able to fix the playback enough to know that Walter must find a mine in the area, which Edwin identifies as an abandoned gold mine.
In the mine, they find a shaft to a lower level; hanging from a rope is a corpse showing extreme signs of the bark infection, which Walter believes is due to something in the mine and evacuates everyone. In examining the body, Walter determines that the condition is caused by the Observers' modification of the Earth's atmosphere, the effects being diluted due to the remote location; the atmosphere in the mine accelerated the process, calcifying the body. Edwin discovers that, sometime in the past, the Observers took away a man, identified only as "Donald," who had retrieved red-colored rocks from the mine with the intention of delivering them to a "scientist from Boston." Astrid later confirms that the rocks are a unique and necessary energy source for Walter's plan. Walter begins to prepare a protective suit to keep the effects of rapid calcification from affecting whoever wears it, allowing them to recover more rock samples. While working on the suit, Peter and Olivia discuss the events shortly after the Observers' arrival, with Olivia revealing that seeing all the "missing persons" posters while they were looking for Etta had made her realize that her work with Fringe division in fighting the Observers was more important than getting Etta back.
Meanwhile, human Loyalists discover evidence of the Fringe team, and report it to the Observers, who set off to capture the team; one of the Loyalists is actually a mole, and contacts the underground to warn Etta of their approach. With time short, the only way to get the right materials for the suit is to barter with another nearby refugee camp, a step Edwin is reluctant to take; he would rather see the Fringe team leave instead. However, Edwin's son River, who idolizes the Fringe team, accuses his father of never helping and runs off. Edwin realizes his mistake, and makes contact with the other camp, then later has a heart-to-heart with River about no longer just being a recorder of history but becoming part of it. Edwin gives Peter and Olivia directions to the other camp and bartering goods, but when they arrive, they find the spot empty, and Peter realizes it was a deception. Meanwhile, at camp, Edwin goes to the mine alone to recover the rocks; by the time Walter and Etta discover this, Edwin has been able to bring enough of the rocks out of the lower level, while his body succumbed to the calcification at the bottom of the shaft.
As the Fringe team escape with the mineral and return to the lab, abandoning their van to deceive the Loyalist forces, River takes over for Edwin as the recorder, writing a eulogy for his father.