The story take place in Swamp thing vol. 2 from issue 151 to issue 158.
It follows how Alec Holland, just after acquire the power of the parliament of stones must help the soul of Anna, a frustrated writer and failed elemental for the parliament of waves,(water elementals), to finish the endings of her stories, compilated in an unfinished book called "River Run".
Swamp thing agree to travel inside the stories, (following the path of the river where Anna's body was found) and finish them. But with each tales, he discovers than the stories say more about him and not about Anna. Must be noted than many of the tales are reminiscence of previous DC alternate universes (earth-X, earth-prime, earth-two) but each one is a twisted tale with alternate versions of the earth elemental.
Eventually the Swamp thing discovers than everything was a ruse: the Parliament of waves was testing him. The water elementals wanted to discover if Holland was worthy of their power.
After confront the parlament, Holland make them free the soul of Anna but only by taking his place as holding the power of the elementals. His path to godhood had started.