Quincy, Lee and Danny are all in Lake Tahoe together. Quincy is there for a forensic Pathologist convention and the others for a weekend break. While they are there the guests and staff start coming down with some kind of strange illness. Quincy and a couple of other Forensic Pathologists are called in to help but when some of the patients start dying they still have no clue as to what is killing them. To make things worse the casino owner does not want to admit that anything is wrong, as it will affect his bookings and profits.

The disease continues to spread and the rest of the hotel/casino's guests want to know what is going on. They want to get out of the building but Quincy and his colleagues know that they have to keep the disease, and the guests, contained. If the disease gets out of the hotel it could cause an epidemic that could quickly spread all over the country!

A thigh bone is found buried on the building site of a new student union building. Quincy is teaching a class at the university and soon involves himself and his students who the bone belonged to, how they died and possibly even who killed him. Not surprisingly Monaghan and Asten consider this a complete waste of time and want Quincy to get back to his job and stop bothering them.

Quincy and Danny go on a fishing holiday to the beautiful lakeside town of Paradise, free from their troubles of restaurant managing and Dr. Asten. Almost as soon as they have started fishing a young woman pulls her boat alongside them and thanks Quincy for coming to investigate her mother's murder! Quincy has no idea what she is on about but is affected by her pleading and agrees to look into it.

In a court appearance Quincy comes up against his old professor, Dr. Herbert Stone, who is an expert witness for the defence. Stone comes up with a completely different view of the medical evidence to Quincy, which cause him to become confused and unsure of his own opinion. Because of this the prosecution loses. Later they appear to be on opposite sides again in another case. Stone refutes evidence that Quincy has found that shows that a rich businessman died in a fire. Quincy is upset when the Assistant DA points out that his old professor is now just selling his expertise to whoever will pay him.

Outside Danny's bar a man is the victim of a hit and run. The woman driving, or thought to be driving, the vehicle was Robbi Parker. She was a friend of Quincy's current girlfriend, Jenny. Danny wants Quincy's help because a new Californian law means that if he served Robbi drinks and allowed her to leave drunk he could be closed down.

Quincy examines the body and finds out that Robbi had had extensive plastic surgery, it also seems as if she didn't exist up until four months ago!

Asten's wife Melissa picks up a young boy wandering at the side of the road at night. Soon afterwards they are involved in an automobile accident. Quincy is told, Asten is out of town, and he goes and visits Melissa, and the boy. As soon as he sees Joey's bruises he knows that they are not new ones caused by the crash, they are older and look like being beaten caused them. He looks at the x-rays taken of the boy and they confirm his opinion that the boy is being abused, probably at the hands of his parents.

After a talk at a university a student who wants his advice approaches Quincy. He thinks that a body that was donated to the university was murdered, that he didn't die accidentally as the records show. What makes it worse is that the body came from a top security prison wing, where the man was being held for his own safety at the time.

Quincy is called in on his day off after a car crash victim is brought in and seems to have an extremely high level of radiation in his body. Ray Sanchez, who was helping out the now man, Bigelow, is arrested for manslaughter, even though Quincy is convinced of his innocence and makes no effort to hide his viewpoint.

To help Sanchez Quincy decides to look more into the radiation aspect of Bigelow's death and tries to dig into his background and find out where he worked.

A well-known priest, who is running a crusade against pornography, is found dead in the room of a prostitute. She insists that he had a heart attack while she was ‘with' him. Monahan cannot believe that Father Terrell would have betrayed his principles and wants Quincy to look very closely when he autopsies the body. Quincy finds some discrepancies and wants to do a more detailed investigation, starting with Carlo Dicassa, noted pornographer and enemy of the father.

An old man dies in a sanatorium, Valleyview, seemingly of a coronary. His grandson doesn't think that he could have died that way and pays for the Medical Examiners office to do an autopsy. Quincy does the autopsy and tells David, the grandson, that there is nothing unusual about the death. All is done with until a young girl, Anne Freedman, dies at the sanatorium as well. Again the cause of death is not clear and Quincy begins to think that maybe someone is performing ‘mercy killings' on patients that are in pain.

A suspected rapist seeks revenge on Quincy by attacking his friend