Beneath the Crooked Hills

A week ago, we had another session of our Land of Azurth 5e campaign. The party had become much more interested in the trinkets and where they might come from. The townsfolk really didn't know, but mentioned a mage who had been looking into the mystery. Unfortunately, she had disappeared.

The party searched her old residence and found some cryptic notes they couldn't make much of. There was also some sort of design or pattern imprinted on a rectangle of an unknown, transparent material. They did discover she had gone into the Hills and never came back.

Knowing there's nothing for it but to explore their selves, they look around until they stumble upon some fissures with foot prints around it. It's a tight squeeze, but they are sure that's where the strange sleepwalkers came from. The party goes in, but it takes a bit of time because Dagmar gets stuck. With they seem a weird glass wall and hear ethereal music. In the next room, they fight a nest of oversized snakes from a pile of debris, before figuring out how to open a door into an octagonal room. There, each wall is adorned with a symbol, and there's a wooden ball in the middle of the room. 

With some investigation, they find a hidden panel that seems to provide some sort of control over what the room does. They eventually decide to put the ball under a symbol matching what the "control panel" shows, and a another, secret door opens.