This stream of Quern picks up in a stone room the game calls Corridor, where a crystal in a holder shoots a beam and turning dials in the walls bend it from room to room. Most of the video goes to getting that beam where it needs to go, first in the Corridor and then in the Underwater Corridor. After that comes a diving suit, a walk on the sea floor, a lock of number dials, and a long story told by a voice in the tunnels. It ends with Basket heading back to meet that voice at the entrance.
Steering the beam
A copper plate on the wall shows a line through a few circles, splitting off to round markers lettered A, B and C. Out in the corridor are dials that turn, each one either sending the beam straight through or around a bend. "We're going to be pulling up our notes a bunch," the commentary says, and does: each dial gets set to match a part of the plate. With them lined up, the beam reaches the far end, a glowing hand appears, and clicking it teleports Basket on.
The Underwater Corridor
The next room brings up "Area Discovered: Underwater Corridor," a glass dome with water outside. Its dials have more settings, and the plate here runs to D and E. The way to D looks blocked by something big.
The first tries don't line up, and the commentary decides the plate is a mirror of the dials on the far wall: "It's mirrored, I guess." Then a red crystal sits in the holder, and the commentary calls its red beam fire. "So now I am shining fire through." The commentary reports a loud gong and a burning rope, and later: "We can see the gong is on the floor because I burned it."
Getting from C to D after that takes a long time. The notes say one thing, the dials do another, and the beam keeps looping back. "I don't understand how I've already done this three times." In the end the commentary settles on "I think I was putting it in wrong." The beam goes through and the hand teleports Basket into what the commentary calls an "underwater hideaway."
A suit and the sea floor
The hideaway has a diving suit. In it, the view shrinks to a round helmet window, and Basket walks out onto the sea floor. Outside, levers get pulled until, in the commentary's words, "we have turned down all three lights to the pipe." Back inside, the water drains and a wall lights up with a grid of numbers under letters across the top.
Out on the sea floor are small round markers, each with a number on top and a code below, like "4" over "ID9." The commentary copies them into the notebook and matches each code to a number in the grid. But the machine with the number dials has five of them, and only four markers turned up. A second walk outside finds no fifth one.
Inside, there is a letter not read yet. Its writer "originally built this facility to explore the depths of the ocean," and says "this was the only place where I could hide from her."
The first full guess does nothing. "More layers to my puzzle than I thought." Then something in the room makes the 1 and 2 in front of the letters click for the commentary, the dials get set again, and this time it works: "I got it." Out comes the gear the commentary was expecting, and it goes into a slot by a ladder to open the next area.
The Shrine of the Seekers
A voice takes over from here, with subtitles. "I remember when this bridge collapsed not long before you came." A floating light leads down through dark tunnels, with "Don't look down" on screen. The subtitles name the place: "the great hall of the Amma'jat. The shrine of the Seekers." Blue crystal powder is needed for the fire. Basket finds a key and some blue crystals, and works a crusher and then a grinder to turn them into powder. "Now use the crane up there to throw the powder into the fire," the subtitle says.
Then the voice tells "the story of my people" while glowing figures play it out. Three were chosen: "Rhoren, the most skilled warrior, Tiador, the brightest of all scholars and a devoted shaman, me." They went looking for "a legendary place of great power, Quer'nelok," and the story runs through a war won in seconds and a falling-out among the three. "It's quite the story," the commentary says.
Where it ends
"It is time for you to return to his path," the voice says. "I'll meet you back at the entrance." The video ends with Basket partway back through the dark tunnels.