The Silent Whispers - Sam Mercer P.I. Investigations, #3

The Silent Whispers (Book 3 in the Series)In the dark underbelly of the city, whispers of a terrifying new threat emerge. Detective Sam Mercer thought he had seen it all, but when a series of inexplicable, silent deaths begins to plague the West End, he finds himself drawn into a conspiracy that reaches into the shadows of his own past. Victims are found dead in their homes, their faces frozen in terror, with no signs of struggle and no sounds recorded.
It's as if the very air around them conspired to kill. The Silent Whispers (Book 3 in the Series)In the dark underbelly of the city, whispers of a terrifying new threat emerge. Detective Sam Mercer thought he had seen it all, but when a series of inexplicable, silent deaths begins to plague the West End, he finds himself drawn into a conspiracy that reaches into the shadows of his own past. Teaming up once again with the determined Evelyn Blackwood, Mercer delves into the sinister world of WhisperNet-a long-abandoned government project designed to weaponize sound.
As they uncover the dark secrets of the project, they realize that its deadly technology has been revived by a shadowy figure known only as "The Whisperer." With the lives of countless innocents at stake, Mercer and Blackwood must navigate a web of deception, betrayal, and murder to stop The Whisperer's plan. Their investigation takes them from the grimy streets of the city to the hidden labs of brilliant but twisted scientists, and finally to a remote, fortified estate where the mastermind behind WhisperNet is pulling all the strings.
Along the way, they confront old allies, new enemies, and a conspiracy that threatens to engulf the entire nation in a silent reign of terror.