The book tells of teenager Vicky Austin and her struggle to understand life and significance in the universe as she deals with her dying grandfather, while at the same time finding true romantic love.

Also present are the commander's wife, his sons Leo and Jacky who own a launch boat business, and Adam Eddington, an intern at the Island's research base and friend of Vicky's brother, John.

Finally Adam takes her into the ocean, where Vicky's dolphin friends break through her mental darkness, until she is able to play with them and face the light again.

Slowly dying from leukemia, Grandfather Eaton encourages Vicky to enjoy life while developing her talent for writing, and only gradually begins to make unreasonable demands as his own mental clarity starts to fail.

Having lost his father, Leo Rodney questions his previously comfortable faith, while taking responsibility for the family's income.

Zachary, whose mother died recently, alternately courts death - driving too fast, flying recklessly in a plane - and runs away from it.

Adam, who holds himself responsible for the death of Joshua Archer the previous summer (in The Arm of the Starfish) because he trusted a girl, is reluctant to open his heart and risk being hurt again.

Related to this is the theme of religious faith in the face of death, a problem Vicky previously confronted in The Moon by Night.

Concurrent with The Moon by Night is The Arm of the Starfish, a book from the O'Keefe family series that takes place the same summer as the Austins' camping trip.

[4] In 2002, the Disney Channel made A Ring of Endless Light into a made-for-TV movie starring Mischa Barton and Ryan Merriman.

Whole-cloth additions to the story include Adam and Zachary teaming up to save dolphins from illegal drift nets, and Vicky being under pressure to study science in order to gain admission to an elite school.