Get to the Yukol caravan (left from the central point) and find the shaman's yurta (the third ostrich on the right, Oscar is standing next to it). Enter using the ladder and talk to Ayawaska. She's not going to be especially talkative - when she falls asleep, search her chest (on the right). Move the junk there to uncover the Ayawaska's staff.
Exit the yourt and go to Kate's quarters - her yurt is at the back of the caravan, more to the left; there's a ladder there as well. From the chest at the entrance, take the lighter and knife.
Go back to the checkpoint, but don't leave the building - enter the mysterious ring on the right, near the river - surrounded by dark stones, with red floor. There's a sort of a furnace, or, as Ayawasca puts it, the old machine of the ancestors.
Emitting smoke signals
Check this furnace out carefully, it's this thing that will deliver the message to the shaman.
Start from the top - the four chimneys. Zoom in on each and turn them right with the mouse. The lowest handle should be switched into a vertical position. Press the button to open the doors. Form the first one from the left; take a chunk of yellow and blue resin. From the third one, take another chunk of yellow resin. Numbers 2 and 4 are empty.
Now, the lower section of the furnace. Zoom in and open the door with the button. From the higher shelf on the left, take a chunk of red resin and a bigger round chunk of blue resin. From the lower one, take three funnels: 01, 03 and 04. Also, take the log which is on the right hand side, and place it in the central part of the furnace. Combine that with the customs officer's papers and light it up using the lighter from Kate's yurta. Close the doors.
See that there's a pipe coming out? It's just above the ground, on the left. Turn the damper so that it's set vertically (as above), so that the exhaust leaves the furnace only through the four chimneys. Exit the zoom.
Now approach the chopping block that stands opposite to the furnace. Zoom in and place the round chunk of blue resin there. Use a knife (if you have, use the one you took from yurta), and cut out a small chunk of blue resin so that you've got a quarter like the other ones.
Go back to the furnace, zoom in and place (the active point in the middle) Ayawaska's staff there. Zoom in o the staff, and you will see a clue as to the color and the shape of the smoke that you need to produce. Start from the colors. The first chimney - red resin. The second and third - blue; the fourth - yellow.
It doesn't matter where you place the chunks themselves inside the pipes. What matters is how you set the upper and lower round grates. Raise the upper one to gain access to the lower.
The whole in the lower one should correspond to the position of the resin on the upper one - so that the smoke is able to get dyed. Make sure all of these are set in such a way.
When you do, lower the upper grates and close the door in all four chimneys. Make sure the lowest knobs are set to vertical (so that air is fed to the chimneys).
Now open the shelves and fill them with saw dust that you got from the metal basket that came across the river in exchange for the vodka. Close the drawers.
Now change the perspective so that you're able to see the back of the furnace. Note that the second chimney from the left (in this perspective!) is open at the back (hence the smoke isn't coming out). Zoom in and take out the funnel 02. According to numbers (and the shape of it) this one should go to the third chimney (looking from this pespective) from the left. All the funnels should be located according to their numbers - if you count when looking at the furnace from the back, you should count from right to left.
So, place funnel 01 into the first chimney on the right, the funnel 02 to the second, 03 to the third, and 04 to the forth. Each of the chimneys has to be opened with the button - then you enter the funnel and close the door.
This should be enough for Kate to send the right message to the watcher (achievement Mobile communication; you get it if the smoke doesn't disappear, even for a moment - you can't allow for a situation in which all four furnaces have closed exhausts at the same time, the same goes for the pipe that comes out from the left side of it).).
(For reaching the end of the game, you get the achievement What counts is not the destination).