London psychiatrist Joseph O'Loughlin seems to have the perfect life. He has a beautiful wife, an adoring daughter, and a thriving practice to which he brings great skill and compassion. But he's also facing a future dimmed by Parkinson's disease. And when he's called in on a gruesome murder investigation, he discovers that the victim is someone he once knew. Unable to tell the police what he knows, O'Loughlin tells one small lie which turns out to be the biggest mistake of his life. Suddenly, he's caught in a web of his own making.