4625 kHz

Since 1982, the Russian military has broadcast a mysterious, repetitive buzzing tone on the shortwave frequency 4625 kHz. For forty years, the world thought it was a spy station.They were wrong. It's a containment system.Renata Kaplan is the NSA's most brilliant pattern-recognition analyst. When a mathematically impossible sub-frequency begins bleeding through the famous Russian "Buzzer" broadcast, she uncovers a secret that bridges the height of the Cold War with an ancient, terrifying discovery deep beneath the Ural Mountains.The signal isn't a military code. It's a countdown. And after forty years, the containment is failing.Drafted onto a classified JSOC team and pushed into the abandoned, subterranean depths of the Soviet Union's most heavily guarded bunker at Mount Yamantau, Ren is about to discover what happened to the four teams sent down before them.Deep in the rock, the signal is waiting. And it wants to be heard.For fans of Blake Crouch, Michael Crichton, and Robert Ludlum, 4625 kHz is a terrifying, relentlessly paced descent into the intersection of modern espionage and cosmic dread.