A missing artist has painted a fantastic mermaid portrait that is taking the art world by storm. Larry Settlebottom, a lonesome Chicago museum curator, is hired to find the artist and his model at any cost. His encounters with sea pirates, exotic gypsies, and oceanographers lead him toward a secluded island with a secret guarded by a madman. Did mermaids once inhabit the Earth? To unravel the mystery, Larry must also face his own buried past.