This is the search for the Caravan Bestiary: the book of lost beasts, the animals that did not make it onto the ark. Like those animals, it is assumed this book has been lost forever. The man seeking it also feels lost himself.

Xeno Atlas is a motherless child; his mother died in childbirth. His father, a seaman, is distant on the rare occasions he is home. Xeno is raised from birth by his maternal grandmother, who acclimates Xeno early on to the possibility of the existence of fantastical animals. ("Who can clearly separate the fantastical from the commonplace? Who would want to?") It is said that she, herself, is descended from a wood nymph. After his grandmother's death, Xeno is established in boarding school and sees his father only infrequently, though all his financial needs are met.

A history teacher sparks Xeon's scholarly research into the subject of imaginary animals and fans the flame years later when Xeno convalesces with him in Hawaii after being injured in the Vietnam War.

("At the Hamilton Library in Honolulu, on June 2, 1972, from an incidental passage in a forgotten text, I had moved the whereabouts of the Caravan Bestiary forward a full century, into the 1340s, and established its last confirmed location on Rhodes.")

Christopher's descriptive style elicits emotional response. We can feel Xeno's loneliness and sense of abandonment by his father, his maternal uncle, and even his mother. We can rejoice in his finding love and acceptance at the end. This well-researched literary piece is similar in theme to Christopher's earlier novel A Trip to the Stars, and it is just as satisfying a read.