Following the strong metal detector signals at the Mercy point in the previous episode, the team returns to the swamp with a Deepmax X6, a far more sophisticated detection unit capable of scanning to a depth of nearly 40 feet and identifying the type of metal present below the surface. Rick and Marty's nephew David and his friend Will walk the coil across the swamp on plywood boards while Rick follows behind wearing a data recorder. At the Mercy point the device registers full-scale readings, mimicking the earlier hits from Steve Zazulyk's handheld detector. In the War Room, Steve walks the team through the computer analysis. Nonferrous metals such as gold and silver appear as orange or red on the screen, while ferrous metals like iron display differently. The results show extensive red and orange returns at the Mercy point across multiple depth layers, covering an area Steve estimates at roughly 100 feet. He confirms the swamp is an area of significant interest.
To investigate the returns physically, Rick and Marty bring in Divemaster Tony Sampson. The conditions are brutal: more than four feet of organic muck at zero visibility, requiring Tony to work entirely by touch. He wears lighter gloves to feel his way across the swamp bottom using a small handheld metal detector. The team clears vegetation with rakes and shovels to help him submerge. Rick and Marty both jump into the swamp themselves to assist, working shoulder to shoulder in the muck. Tony's detector picks up multiple hits, and audible pings can be heard above the water. He surfaces once with a large piece of rock, but the most significant moment comes when he recovers a small copper object from the mud.
The object appears to be a coin. An eight is visible on its surface, and Rick recognizes it as something he has seen before, possibly a Spanish maravedi dating to the 1500s or 1600s. The find sends a charge through the team. For over two hundred years, treasure hunters have recovered wood, coconut fiber, scraps of metal, and other circumstantial evidence from Oak Island, but never a single coin. A local legend about Anthony Graves, a wealthy 19th-century island landowner who reportedly paid for goods on the mainland with 17th-century Spanish coins but refused to say where he got them, adds historical weight to the discovery.
Rick and Marty take the coin directly to Dan Blankenship. After nearly 48 years of searching, Dan holds in his hand the first solid evidence that people may have been on Oak Island before 1795 and that they may have buried treasure there. Dan is visibly moved and declares it confirms his long-held belief that the Spanish were responsible, placing their activity on the island between 1500 and 1550. He then passes the coin to his son David, a gesture that strikes the team as a passing of the torch. Charles Barkhouse, who has researched the find, identifies it as a Spanish maravedi eight cob, probably from the 1600s. The date on the reverse is obscured, but Charles believes it predates the Money Pit by at least 150 years.
Back at the Fo'c'sle Tavern, the team gathers for a final meeting. Marty reveals that had the coin not been found, he was prepared to ask Rick to call off the search. The discovery changes everything. A vote is taken on whether to continue, and every hand goes up. Craig Tester's son Jack, Alex Lagina, Dave Blankenship, Charles Barkhouse, and Dan Henskee all commit to returning. For Rick, who has spent his entire adult life trying to convince his brother that Oak Island is real, the moment is a validation decades in the making. The team resolves to come back and follow wherever the evidence leads, whether that means returning to the swamp, Smith's Cove, Borehole 10-X, or the Money Pit itself.
