Savant

Tim Grayson, a temperamental, socially awkward young genius, would rather not be famous—but it's too late now. A documentary chronicling his freakish brilliance in math and music has just won an Oscar, and random strangers now recognize him on the streets of Manhattan.

Tim takes refuge from the world by playing intimate duets with his violinist friend, Rachel. But the tranquil bliss of their music is shattered one evening when Tim suddenly sees a dark silhouette of a man standing behind her and panics.

His visions of a man only worsen with time, haunting him everywhere he goes and warning of impending doom. Meanwhile, another shadowy presence stalks him—the corrupt CEO of a private security firm has sent a remorseless covert agent to monitor Tim's activities, searching for a way to exploit his fertile mind. But that mind unravels by the day, with Tim's visions increasingly blurring the line between horrific madness and an even more unspeakable reality.

This is the first book of the Savant series.