Life Expectancy by Dean Koontz is a daring leap into the darker side of human nature. When Rudy Tock and his wife, Madelaine, go to the hospital to have their son, Jimmy, events coalesce that will affect this family for many years to come. Rudy's father, Josef, predicts five terrible days in Jimmy's life right before he dies, which happens just as Jimmy is being born. At the same time, Jimmy's father, Rudy Tock, meets another expectant father in the hospital - Konrad Beezo. Konrad is an unhappy clown from a traveling circus who believes that a group of aerialists are out to get him because he married one of their caste. Konrad's wife dies in childbirth at the same time as Jimmy is born, and Konrad loses touch with reality, shooting the doctor and one of the nurses involved in his wife's care before taking his new born son, Punchinello and disappearing from the hospital.

Jimmy lives with his mother, father and grandmother until the first of his five terrible days arrives but being taken hostage by a crazy gunmen is the event that introduces him to his future wife. The gunman is revealed to be Punchinello Beezo who ends up in jail after killing his two cohorts. Jimmy and Lorrie get married and face the next four terrible days together, each one crazier than the one before. On the second of five terrible days as predicted, Konrad Beezo burns down their house, telling them they owe him a son but instead they have a daughter. On the third, Lorrie is shot by Konrad who returns insisting they give up their fourth child and first son, Andy, for training as a clown. Konrad is killed by Jimmy and Lorrie is told she can no longer have children as a result.

The fourth terrible day has Jimmy and Lorrie entwined with the Beezo family again, but this time in ways they could never have predicted. They discover the Tock's son Jimmy was actually stillborn and the child who lived his life is actually one of the Beezo twins born to Natalie Beezo and switched by a nurse after her death. Now they need Punchinello's kidney to save their daughter's life. He finally agrees, providing his brother Jimmy kills his arch nemesis, Virgilio Vivacemente - the aerialist. Jimmy agrees, never intending to do so. The fifth terrible day brings them face to face with Virgilio in a conclusion that is completely unexpected! Jimmy learns more about his lineage he never suspected, and decides that none of it matters. Good triumphs over evil, and love and laughter are unending. The conclusion is filled with unexpected revelations that finish a tale with many twists and turns and packed with surprises. Prepare to be enchanted!