Looking for clues

There were 3 different passages inside. They each entered a passage and started looking around separately, but they did not encounter any creatures. But at a midpoint where the passageways in the entire cave were connected, the group got together again.

From here on, there was only one passage that went deeper into the lair. The group quickly continued to advance through this passage. When they went 50 km deeper, the temperature inside had risen. The temperature continued to rise and was almost hot enough to turn a normal person into coal in a second.

Ailen was out of breath because she was the weakest among them and did not have the energy of water. She was not able to go any further. With her depression and frustration, the young girl stopped going any further. "I have no strength left to go further from here. From now on you will have to continue without me."