The mystery?🤫

Previously

…The answer, he realized with a sickening certainty, was not a stranger, not an outsider. It was someone who had been a constant, unassuming presence in Alistair Finch’s life, someone whose ambition and resentment had been masked by a facade of quiet competence, someone who had watched, and waited, and planned with chilling precision. The shadow had not been cast by a distant enemy, but by a familiar face, hiding in the blinding light of everyday life. He looked at Eleanor, her face a mask of fear and a dawning, terrible understanding. The real killer was still in the room, metaphorically speaking, and Corbin felt the trap closing.