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Cow Skull door (Film Canister 2 and the white door)

Updated 17 Oct 2026 · Game version: launch version (Oct 16, 2026)

The answer in one line

Take Film Canister 2 from Iván's childhood room on floor -1, play it on the projector, take the Cow Skull from the new theater box and use it on the white door at the far left past the first door up the dining-room stairwell; the boss Fumus waits behind it.

Missing something, or nothing happens? The steps are below.

Our pencil sketch of this puzzle goes here.
We draw the sketch once the puzzle is checked in a playthrough.

Where the puzzle is

The canister is down on floor -1, which you reach through the elevator color code. The door is back on the 1st floor: up the stairwell to the right of the dining room, through the first door, at the far left end.

None of these steps appear in the puzzle-guide video. They are pieced together from iampanax's full walkthrough and the Gamer Social Club text guide, so room-by-room details may be slightly off.

Not sure you’re in the right place? Search for your room in Quick find tool.

What you need

  • Film Canister 2: Iván's childhood room on floor -1
  • Cow Skull: the theater box that opens after Film Canister 2 is played

Exact spots for each one are on Items and collectibles.

Step by step

  1. Get Film Canister 2 on floor -1

    From the elevator on floor -1, head right through the corridors until you reach Iván's childhood room, and pick up Film Canister 2 there.

    Inferred: pieced together from our sources, not shown step by step in a video

  2. Play it and take the Cow Skull

    Go back up and run the reel on the projector, the same way as the first canister. A second box opens in the theater; take the Cow Skull from it.

    Inferred: pieced together from our sources, not shown step by step in a video

  3. Use the Cow Skull on the white door

    In the dining room take the right door into the stairwell, go through the first door and walk to the white door at the far left. Use the Cow Skull on it. A boss fight with Fumus follows; beating him gives the Red Pentacle Stone, which later puzzles need.

    Inferred: pieced together from our sources, not shown step by step in a video

If it doesn’t work

No new box opened in the theater.
Only Film Canister 2 opens this box. Make sure you played the second reel, not the first one again.
I can't find the white door.
Start from the dining room, take its right door to the stairwell, then enter the first door. The white door is at the far left end of that hallway.
A monster attacked as soon as the door opened.
That is Fumus, the boss behind this door. Defeat him to get the Red Pentacle Stone.

Sources

  1. Tenebris Somnia Full Game Walkthrough - All 4 Endings [No Commentary] by iampanax Timestamps used: 1:32:23 (Film Canister 2), 1:39:25 (Cow Skull), 1:44:23 (Fumus)
  2. Tenebris Somnia Full Puzzles Walkthrough (Gamer Social Club, used to confirm the Cow Skull steps) by Mark Pell

Spotted a step that’s wrong? Tell us and we’ll fix it and update the date.

indiewalkthrough isn’t affiliated with Andrés Borghi & Saibot Studios or New Blood Interactive.