You're standing in a damp, torch-lit cavern deep beneath the Lake Canulus region. The air feels heavy. Ahead of you, a group of fanatics in crimson robes chants to a Daedric Prince. It’s one of those moments in The Elder Scrolls IV: Oblivion where the stakes suddenly feel incredibly real. We are talking about the Dagon Shrine quest, a pivotal turning point in the Main Quest that basically flips the script on how you’ve been playing the game up to that point. It isn't just another dungeon crawl. It’s a test of whether you can actually play the role of an undercover agent without blowing your cover—or if you’re just going to go in swinging a claymore and hope for the best.
Honestly, the first time most people play this, they mess it up. You think you’re just going to walk in, grab the Mysterium Xarxes, and leave. But Bethesda designed this specific mission to be a masterclass in atmosphere and choice. It’s the "Path of Dawn" segment of the story, and if you haven't done it in a while, you might have forgotten just how tense it gets when Harrow asks for all your gear.
Getting Into the Lake Arrius Caverns Without Dying
To even start the Dagon Shrine quest, you’ve got to talk to Baurus in the Elven Gardens District. This leads you through a whole "spy movie" subplot involving a sponsor and a book. Eventually, you find yourself at Lake Arrius Caverns.
When you approach the door, a cultist greets you. This is the first major fork in the road. You can play along and pretend you want to join the Mythic Dawn, or you can start hacking and slashing immediately. If you choose the "Infiltrator" route, you have to hand over every single item in your inventory to a guy named Harrow. Every potion. Every lockpick. That ancestral sword you spent three hours soul-trapping for? Gone.
It's a gutsy move by the developers. It strips the player of their power fantasy right when things are getting dangerous. If you’re a mage, you’re fine—you’re the weapon. If you’re a heavy armor warrior who relies on a shield? You’re suddenly feeling very naked in a room full of people who want to sacrifice you to a four-armed fire god.
The Sacrifice of Jeelius
Once you’re inside, you’re led to the inner sanctum. This is where Mankar Camoran—the big bad of the game—is giving his sermon. He talks about "Paradise" and the "Lesser Realms." He’s voiced by Terence Stamp, and his performance is genuinely chilling. He then disappears through a portal to Gaiar Alata, leaving the Mysterium Xarxes on a podium.
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But there’s a catch.
Ruma Camoran, Mankar’s daughter, hands you a silver dagger. She tells you to kill an Argonian named Jeelius who is tied to an altar.
- You kill Jeelius. This keeps your cover intact for a few more minutes. You can then grab the book and try to sneak out.
- You refuse. The entire room turns hostile instantly.
- You wait. If you take too long, they get suspicious anyway.
Most players try to save Jeelius. Why? Because it’s the "heroic" thing to do. But saving him makes the escape ten times harder. He’s weak, he’s panicked, and he has zero combat skills. If you want to keep him alive, you basically have to act as a human shield while half a dozen Mythic Dawn agents pelt you with sparks and silver daggers.
Managing Your Inventory After Harrow Takes It
The biggest mistake people make during the Dagon Shrine quest is forgetting where their stuff went. Harrow is the NPC who takes your gear. If you kill him during the chaotic brawl that ensues after you grab the book, his body will have all your items.
However, if you aren't careful, his body can get lost in the water or tucked behind a rock. I've seen forum posts from 2006—and even as recently as last month—where players thought their items were permanently deleted. They aren't. But you must loot Harrow. If you run out of the cave without looting him, and the cell resets, you are starting your life over from scratch in Cyrodiil. That’s a rough way to learn a lesson about inventory management.
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Stealth vs. Brutal Force
Is it possible to sneak through the whole thing? Kinda. If you have a high enough Illusion skill, you can use Invisibility or Chameleon to snag the Mysterium Xarxes and bolt for the exit. But the game scripts certain NPCs to notice the book is missing.
If you go the "Brutal Force" route from the very beginning, you never give your gear to Harrow. You just fight your way through the front door. This sounds easier, but the Mythic Dawn members in the shrine are actually leveled. If you are level 20 or 30, they are wearing Bound Armor and summoning Daedra. It becomes a meat grinder. The "Infiltrator" path is actually the intended experience because it builds that sense of dread.
Why the Mysterium Xarxes Matters
You aren't just stealing a random book. The Mysterium Xarxes was supposedly written by Mehrunes Dagon himself. In the lore, this book is what allowed Mankar Camoran to create his own "pocket realm" of Oblivion.
When you finally get it back to Martin Septim at Cloud Ruler Temple, he’s terrified of it. He won’t even touch it without "precautions." This is a great bit of world-building. It reminds the player that even though you’ve been running around killing mudcrabs, you are now messing with primordial forces that can unmake reality.
Pro Tip: Don't try to read the book in your inventory. It doesn't work like a normal skill book. It’s a quest item, and its power is strictly for the ritual Martin needs to perform later.
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Common Glitches to Avoid
Oblivion is a Bethesda game, so obviously, it has some quirks. During the Dagon Shrine quest, there is a known bug where the gate won't open if you kill the guards too quickly.
If you’re on PC, you can fix this with console commands, but on Xbox or PlayStation, you might be stuck. The best way to avoid this is to let the dialogue play out. Don't "speed-run" the conversation with the door guard. Let him finish his sentence about the "Master" before you move forward.
Also, if you are a vampire, be extremely careful about the timing. The Lake Arrius Caverns are dark, but the moment you step outside with the book, the sun might be rising. I’ve lost more than one save file to "Sun Damage" because I spent too much time looting the cultists inside and forgot it was 6:00 AM.
The Aftermath: What Happens Next?
Once you escape, the Mythic Dawn won't leave you alone. They will occasionally spawn in cities and attack you. You’ve basically become Public Enemy Number One for the cult. This adds a layer of tension to the rest of the game. You'll be walking through Cheydinhal, minding your own business, and suddenly the "battle music" starts because a sleeper agent behind the counter at the general store just pulled a conjured mace on you.
Actionable Steps for Your Playthrough
To get the most out of this quest without pulling your hair out, follow these specific steps:
- Store your best gear: If you are worried about the Harrow situation, leave your most precious items in a chest at your house (like Rosethorn Hall) before heading to Lake Arrius. Only take what you need to survive.
- Bring Soul Gems: The Mythic Dawn agents are great for filling Greater or Grand soul gems because many of them are high-level NPCs.
- Focus on Harrow first: In the big fight, ignore the acolytes. Find Harrow and take him down immediately so you can get your weapons and armor back. You’ll be much more effective once you aren't fighting in your underwear.
- Save Jeelius for the reputation: While he’s a pain to escort, saving him gives you a Fame point and a nice feeling of being a "good guy." If you’re playing an evil character, well, that silver dagger is right there.
- Check the side rooms: There are several chests in the living quarters of the shrine that contain high-level alchemy equipment and random loot. It’s worth the five-minute detour before you exit the cave.
The Dagon Shrine quest remains a high point in RPG design because it forces the player to adapt. It isn't just about how high your Strength stat is; it's about how you handle being cornered. Whether you sneak out with the book or burn the entire shrine to the ground, it’s a sequence you won't forget. Make sure you have a save file from right before you enter the cavern—it's a blast to replay using different tactics just to see how the cultists react to your choices.