The novel masterfully explores the gray areas between right and wrong, particularly through Tom's internal struggle between his duty-bound nature and his love for Isabel. The choice to keep baby Lucy challenges conventional morality and demonstrates how good people can make ethically questionable decisions out of love.

Physical and emotional isolation on Janus Rock serves as both literal setting and metaphor, showing how seclusion can both strengthen bonds between people and distort their perspective on reality. The lighthouse's position between two oceans symbolizes the characters' existence between truth and deception.

The story illustrates how love can both heal and harm, through Isabel's maternal love for Lucy, Tom's devotion to Isabel, and the biological mother's undying connection to her child. These various forms of love drive the narrative and shape the characters' choices, leading to both redemption and tragedy.