C400

"The code only said four words: The dragon is inside the cave." Wang Yuanchao said.

"Dragon?" I was stunned for a moment and looked at Wang Yuanchao in confusion: "What dragon?"

Wang Yuanchao sighed and said, "This signal is too short. It should have been hastily written by that soldier before he died. I don't know what the dragon represents." Was it a code name for a military operation