The Echoes of Obsidian Ridge

CHAPTER 7: 

“It leads to an old timber transport tunnel built into the cliffside,” Maya said, pulling a heavy brass keycard from her pocket.

As she rushed to unlock the rear blast door, Julian noticed a small shortwave radio console on the corner desk pulsing with a rhythmic green light. A faint, low-frequency tone was emanating from its small speaker—three rapid high-pitched notes, followed by two long, trailing low notes, repeating on a precise five-second loop.

Julian stopped in his tracks, his musician’s ear instantly picking up the pattern. “Wait. Maya, listen to that.”

“Julian, we need to move!” she pleaded, holding the heavy blast door open.

“No, listen!” Julian insisted, plugging a pair of monitor headphones into the receiver. “That’s an acoustic cipher. It’s set to a specific frequency—142.08 Megahertz. My dad used to play that exact musical interval on his acoustic guitar when I was a kid to test audio feedback.”

Maya paused, looking at the blinking console. “My mother wrote music scores as a hobby… she used musical notation to encrypt her personal diaries.”

“It’s not an automated alarm,” Julian said, adjusting the frequency dial. “It’s a broadcast loop from a portable transmitter. Your mother set this off manually before they fled. She’s broadcasting their location.”

He cross-referenced the signal strength meter on the console with a local topographical map pinned to the wall. “The signal is bouncing off the relay tower at Blackwood Peak, three miles north through the ridge.”