The miners press on to blast through the back of the Eastern Tunnel in an effort to get at the collapsed mine with its far-richer gold face, discovered at the end of the last mining season. They make their final push by loading the area with extra explosives. As Bucket runs out of the mine shouting, "Fire in the hole," the crew waits for the expected blast to follow. Oddly, nothing happens. Stan and Fast Eddie exchange concerned looks as a fuse misfire could spell life-threatening danger to any miner they send in to check on the issue.
Stan seeks out Kristen and Patrick and asks if they'll send RIPA instead, rather than risk any injury to his miners. The investigators agree and they send RIPA into the mine. As the camera pans around at the fuse, nothing looks out of place. Just then as they start picking up some readings, something sets off the fuse, causing a cascade of explosions from within the mine. As the dust settles, the crew and investigators head in to asses the damage to RIPA. Luckily, she makes it out with only minor damage but the bigger question remains: What caused the delay of the original misfire?
The blast clears out what the miners had expected it to do, but when they head back, they realize it's uncovered yet another old cave-in. With the strangeness of the misfire and fuse re-igniting on its own, Kristen and Patrick decide to perform an investigation. As Patrick gets dangerously close to an unstable area, his K2 meter begins to pick up a number of hits. As they conduct an EVP session, they heard the sound of rocks falling. Fearing for their lives, they run back out of the mine, convinced the mine is caving in.
Stan and Fast Eddie agree to check out that area when seeing just how shaken and spooked the investigators are when they come out of the mine. To everyone's surprise, the area looks the same as it did when they went in; there was no new cave-in. As Stan and Fast Eddie check the rock, they determine it's solid and that Kristen and Patrick were in no danger. They can't explain the terrifying sound of falling rocks from earlier.
Larry pays the investigators a visit, alerting them to issues he's been having with one of the field cameras set up around the camp to try and catch their mystery trespasser. They pull the card from the affected camera to see if there's a malfunction. As they examine the photos, they find that the card is full, but don't see any evidence of something that would have triggered the motion sensors. They do see a strange line that appears in every photo; they go back to the camera that night to double check that there's nothing in front of or on the camera itself.
As they investigate, they don't find anything to explain the strange line. Once again, they begin to hear a few strange knocks and footsteps. They separate as Kristen follows EMF spikes while Patrick chases a series of sounds and images on the thermal cam. Both end up in the same spot as their readings peak, leading them to what looks like the ruins of a former structure that turns out to be directly in the line of sight of the affected field camera. In the rubble, they find a rock covered in strange markings that appear to be Asian in origin. Patrick takes a rubbing of the markings for further examination.
When they get back to camp, the miners are still gathered around the evening's campfire. Patrick shows them the rubbing he took and Stan shares how Chinese miners were used back in the gold rush days. He also reveals that many of those Chinese miners were often brutally murdered for their work instead of paid.
The next morning, Fast Eddie and Jamol find that their mining equipment has been vandalized, again, setting them behind schedule. Meanwhile, Patrick sends both the rubbings and an audio file collected from an earlier EVP session to an expert for examination. Kristen meets with the local historical museum to talk about Sumpter's history with Chinese miners. She learns that in Sumpter alone, there were as many as 3,000 Chinese immigrants there at one point, but because they weren't counted on the census, it's as though they were wiped from history.
At their evidence review that morning, they reveal that just before the misfired fuse detonated, the same-looking glitch that followed Jay around the mine also appeared on RIPA's camera. Patrick shares the translation he received about the Chinese markings: they mean "House of Cremation." The foreign-sounding EVP clip was translated as "I'm lost" from Cantonese. Just as Patrick reveals this, the cook shack is hit by an unseen force. When everyone runs outside, they can't find anyone that would have caused it.
It's clear that something has been disturbed in the mines with all the blasting and now it's letting the miners know exactly how it feels.
Kristen sees the opening in the side of the mountain for herself and makes a startling realization about the way the mine aligns with Baker City.
In this shocking season finale, the miners finally approach the mother lode as Patrick and Kristen reveal the final shocking pieces of the paranormal puzzle.
Stan and Eddie check in with mine owner Larry to outline their prospects for what little remains of the mining season.