Wow, I think I've got something for you.
Or at least something quite close and easy to adapt.
My only OSR adventure centers around an invaded temple of the Bee-goddess Melissa. The temple was invaded by "chaos demons" of sorts.
It is great for low-level PCs, and also as a campaign starter: low-level PCs may rescue the prisoners but cannot fight the main villain immediately.
Here are some facts about the cult FWIW:
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Acolytes are men and women faithful to Melissa that serve the priesthood in the temple. They are ordinary humans. Most of them were killed or captured in the attack. They know 1d4 of the facts below.
Every priestess and acolyte will know about the myths and taboos of their religion: men aren’t admitted to the priesthood, the bond between a mother and her children is sacred, civilization breeds corruption, members of a family should protect each other, priestesses use white and gold robes within the temple, etc.
Roll
Facts
1
Melissa is a goddess of healing, fertility and daylight. She is good to all that seek her blessings.
2
The temple produces a sacred honey that cures wounds and diseases. This honey comes from a fountain within the temple.
3
There is gold and artifacts hidden in the temple.
4
The most important amulet in the temple has the power to summon an avatar of Melissa, or so the legends say.
5
The avatar looks like a giant bee. This aspect of Melissa is dangerous, but it will help those in need.
6
The avatar isn’t meant to dwell in this plane. In the past, it has built giant hives and transformed humans into bee-people before realizing this hurts her followers. It hasn’t returned to this world since, giving only blessings and inspirations instead.
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And one NPC:
ILLARA. AC 13, HD 3D6 [12 HP], MOVE 30, ATTACK: RAPIER (1D8), SAVE 17, MORALE 11.
Illara, “the Bee’s Sting”, is a priestess of Melissa, but unlike others of her kind. She has received the holy (and secret) task of using poison to protect and avenge the temple; in game terms, she is a 3rd level thief (or assassin, etc.). She tried fighting the invaders but was captured with other priestess and acolytes and is trapped within the hive. Even in captivity, she has heard enough to know Zothaq has summoned Malavor, and now her main goal is killing them both. She is carrying a vial of poison (ten doses - see the “poison” section, below).
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Here is the book:
https://www.drivethrurpg.com/product/314393/The-Wretched-HiveAnd here is the free "one page dungeon" version:
https://methodsetmadness.blogspot.com/2015/05/the-wretched-hive-my-one-page-dungeon.htmlHope this helps!