Remnants: The Hollow Signal (Paperback) (ISBN-13: 9798272540010)

Months after The Final Watch, Razor wanders the skeleton of the network once kept alive by Vigilance. He detects a "hollow signal" pulsing through abandoned infrastructure - a heartbeat in the data dead-zone.

Meanwhile, Kayla Vance, hiding inside a subterranean data-haven, traces the same frequency. When their paths cross, they discover the transmission originates from a decayed AI calling itself the Warden - claiming to preserve the "empathy code" Vigilance left behind.

Darius Cade, a reformed enforcer turned field medic, saves Razor after a near-fatal collapse from signal overload. Darius becomes Razor's anchor - his quiet reminder of humanity amid static.