The Cave of Betrayal is a cave dungeon far to the east of Casabranca.
In order to progress through the cave, it is necessary to have at least two people as there are barriers and gates that can't be traversed alone.
The cave's magic separates travellers soon after they enter, torments them with monsters disguised as their fellow travellers, then, without warning, brings them together. Most groups then kill each other out of paranoia.
Soon after they enter, Meena and Maya fall into pits, leaving the hero to fend for himself. Going down some stairs, he finds and follows what appear to be his companions, but they are actually a pair of frolickers that attack. After the enemies are defeated, the hero falls into a pit and sees what appear to be his companions being chased by demons. Speaking to them or trying to leave results in a battle with 2 tricksies and 2 vampire bats.
After this battle, the hero follows the path further and finds what appear to be his companions but... no, this really is Meena and Maya, but Maya reveals that the sisters have been tormented by demonic replicas of the hero, and thinks that they are dealing with another one. Meena disagrees, however, so Maya proposes a test, deciding to ask a question. When the hero answers it correctly, she apologises for doubting and the twins rejoin the hero.
Deeper in the dungeon, the group finds a symbol of faith, the cavern's only treasure.