Those Who Prove Worthy is the ninth chapter of Uncharted 4: A Thief's End.
Knocking over all rock cairns will unlock the bronze trophy Not a Cairn in the World.
After observing and reading the mysterious poetic message written by pirate Thomas Tew, Nate and Sam continue through the icy caverns. They cross a rickety bridge and find a large chamber. Nate steps on a trigger, activating a mechanism that traps the two inside. Facing them is a system of stone wheels with three crosses that pertain to Jesus, Gestas, and Dismas, and a hole with a bucket in it. Nate finds a booby-trapped lever, with a skeleton caught in sharp spikes protruding from the area around the handle. Nate pulls off the arm of the skeleton from the handle and the spikes retract. The wheels change positions, and Nate picks the bucket up and fills it up with water. Sam puts it back in the wheel, thus activating the puzzle.
After solving the puzzle, Nate successfully continues through the caverns. The two brothers eventually find themselves in the catacombs underneath the cathedral. At this place, the explosions being conducted by the Shoreline mercenaries are felt in full force. Nate and Sam continue to navigate through the catacombs until Sam overhears a conversation through a crack in a wall. On the other side, Nadine and Rafe discuss the recklessness of Nadine's men using explosives to excavate the cathedral. Nadine defends her point by saying that the riot at the auction could have been avoided had the cross been acquired beforehand. She also opens up that due to Rafe's inaction, they've lost their advantage over the Drake brothers. Nadine leaves Rafe alone in the room and he expresses his frustration.
Nate and Sam continue through the catacombs to an open cavern. The brothers conclude that there was supposed to be another test waiting for them at the cavern but had collapsed into the sea. They travel across the ravine and continue to a set of stairs that lead them to a huge chamber with a scale at the middle; one side has a jeweled cross and the other has a handful of copper coins. Seeing through the trick, Nate convinces Sam to pick up a copper coin. A mechanism activates to show a holographic map of Madagascar on the floor. Upon noticing further, they notice that a floor ornament lines up with King's Bay in Madagascar on the map. Realizing that the treasure isn't where they thought it was, Sam claims that Avery was trying to mislead them. Nate, however, theorizes instead that Avery was recruiting, with the caverns serving as the initiation and the crosses as invitations. Before they can discuss Avery's intentions for recruitment, Nadine and her mercenaries burst into the chamber and have the duo surrender their weapons.
Nadine informs Rafe of the situation over her walkie-talkie and notices the marker over King's Bay. After Sam tricks Nadine into taking the jeweled cross, the chamber floor collapses, and Nate, Sam and Nadine make it to safety. A firefight ensues as Nate and Sam escape the chamber. Nate and Sam reach the cathedral proper where the fight intensifies. Sully calls them and informs them that they have to get to him immediately as the mercenaries had found him, and are shooting at his plane. Nate and Sam navigate through the ruins and jump off a rock slide that lands them in the frigid Scottish ocean. They climb onto Sully's plane and escape the area.
On the plane, they discuss that the treasure was never in Scotland, and that what they found leads them to King's Bay in Madagascar. Sully asks where in King's Bay they needed to go and Nate refers to the copper coin Sam had picked up. Upon further examining the coin, they find a volcano stamped into it, which refers to an extinct volcano in King's Bay. Sam asks Nate whether Avery was really recruiting and not trying to mislead them, to which Sully also expresses concern. Nate implies that Tew's involvement is tied to his theory, as Tew's reputation was comparable to that Avery's, and they didn't need each other. With Avery recruiting pirate captains, Nate claims that Avery, Tew and other pirate captains hoarded all their loot somewhere. This idea delights Sully, as the hoard would be much more profitable than the Gunsway heist's $400 million. They decide to head to Madagascar immediately.
Upon arriving at King's Bay, Nate calls Elena, who was worried about him as a monsoon had ravaged Malaysia. Nate lies to her about delays caused by the monsoon. Elena suggests coming to Malaysia to help Nate, but he refuses, leaving Elena anxious about him.