The Pentalian Factor is the 23rd Proposed Serial in Spectral Shadows. It is preceded by Serial 22 - Return to the House of Spectral Shadows and succeeded by Serial 24 - Love Kills. It is currently not being worked on, meaning that the only available material is the summary on the Synopsis Page.
The summary is as follows:
Captain Harry arrives in the forest, carrying in his Sound Chaser the last surviving Pentalian equines, who have been rescued from their planet before its destruction. Jon berates him for bringing the helpless Pentalians to such a dangerous place. Captain Harry responds by informing Jon that it is the will of The Omman Lords that The Pentalians be there, and that their safety is now his responsibility.
Because the Pentalian equines are without The Manáge, they are drawn to the human rebels taking refuge in the forest for companionship. One of those rebels is Harrison James, now freed of his curse as The Iron Man.
One of the Pentalian equines becomes attached to Harrison, beginning a very improbable and highly controversial romance. Other human rebels then follow suit and give into the pleas of the equines who will suffer and die if they don't find love to sustain them.
The entire alliance comprised by the forest animals, the escaped research animals and the human rebels become extremely protective of the alien equines. They know that once word of their presence reaches the outside world there will be a stampede of profiteers out to capture them, as well as hate groups who will regard them as an abomination and demand their destruction.
Still they are unable to prevent small hunting parties from penetrating the forest and capturing a few of the equines, one of which is Harrison’s mate.