With modern-day issues explored against a backdrop of horror, The Swamp Thing stories became commentaries on environmental, political and social issues, unflinching in their relevance. Saga of the Swamp Thing Book One collects issues #20-27 of this seminal series including the never-before-reprinted Saga of The Swamp Thing #20, where Moore takes over as writer and concludes the previous storyline.

Book One begins with the story "The Anatomy Lesson," a haunting origin story that reshapes Swamp Thing mythology with terrifying revelations that begin a journey of discovery and adventure that will take him across the stars and beyond.