Bertram Pincus (RICKY GERVAIS) is a dentist who doesn't like people, be they strangers, his patients, or even fellow dentist Dr. Prashar (AASIF MANDVI) who shares the office with him. A no-nonsense curmudgeon through and through, he hates small talk, especially from those involved with his current colonoscopy. When he's done with that, however, a number of people approach, follow and then chase after him, thankful that he can see and hear them.
He thinks he's experiencing post anesthesia hallucinations, but he eventually gets the hospital staff to admit that he was clinically dead for seven minutes during the procedure. And he now realizes those following him are real, except for the fact that they're ghosts with various sorts of unfinished business that's kept them from crossing over.
Chief among them is Frank Herlihy (GREG KINNEAR), a successful man who was hit by a bus and now wants Bertram to break up his widow's pending marriage. It doesn't matter that he was cheating on Gwen (TÉA LEONI) or that her fiancé, Richard (BILLY CAMPBELL), is a human rights lawyer and seemingly a decent man. Frank wants the relationship severed, and when Bertram refuses to help, the ghost makes him a deal -- cooperate and he'll get rid of the rest of the ghosts.
Bertram reluctantly agrees, but as he gets to know Gwen, he starts to develop feelings for her. From that point on, he must decide how to proceed, all with Frank's ghost hanging around, offering advice and generally irritating the dentist.