The book explores a range of paranormal phenomena and advances a philosophy of mind over matter, arguing that the human soul is immortal, and that a person's fate in the afterlife is self-imposed.
When Chris dies, he experiences symptoms of a near death experience. As pain gradually leaves his body, he observes a tunnel of light and views his dead body from above, connected to himself by a silver cord. He then experiences his life flashing before his eyes, as the events in his life unfold in reverse. This last experience occurs again later, much more slowly, while he's a ghost. Albert later compares it to purgatory, a time when people are forced to re-examine their lives without rationalization.
Chris's family contacts a medium who can see but not hear Chris, and they conduct a séance. Chris tries to communicate with them, but tires and goes off to sleep. When he awakens, he is horrified to find himself staring at a figure of himself conversing with the family. The psychic is unknowingly feeding this figure some answers he expects to hear, unaware that he's not conversing with the real Chris. The novel later explains that the figure is the shedding of Chris's etheric body to release his spirit body, enabling him to ascend to Heaven, or Summerland.
Summerland, an environment shaped by the thoughts of the inhabitants, appears relatively Earth-like because that's what the newly dead are accustomed to. Communication is telepathic, travel instantaneous. There's no need to eat or sleep. The inhabitants, all of whom possess an aura, can spend time relaxing, studying, or working — though not for profit. There are scientists and artists, many of whom work to subtly influence the minds of Earth's inhabitants.
Albert, whom the novel identifies as Chris's guardian angel, explains that Summerland includes many things that inhabitants do not need — such as automobiles — but which exist simply because some people believe they are needed. The particular Heaven of each religion exists somewhere, because that is what members of each religion expect.
Albert cannot locate Ann until one of their sons prays. In the lower realm, Albert and Chris can no longer communicate telepathically and must travel by foot, but they are able to use their minds to influence the environment to a degree.
Everyone has had a multitude of past lives; some souls become so advanced, however, that they pass to a higher level where they ultimately become one with God. Reincarnation is a complex process in which one enters a baby's body, though not necessarily at birth.