The narrator wants to brake up with his companies and go his own way. Its a downward spiral. that he is no longer headed to heaven, but for the river Styx.. hence "when the owls cry in the night " and the observation that the rainbows end ..its just a den for those who...hide their loves to depths of lies . The end of the song confirms that the journey is ,in reality. a failure, as if the dream had degenerated little by little into a nightmare, as a result of determined opposition from other people ...they cant hold the wrath of those who walk ...
Led Zeppelin - All the songs - The story behind every track by Jean-Michel Guesdon & Philippe Margotin page 278