In Outsider Space a group called the Movement broke away from local authority, and by joining nanotech and biotech, bioengineered humans, livestock and agriculture for the colonizing other planets.

Two Outsider scientists, Luz and Ian, landed on the surface to look for Movement technology and rescue as many locals as they could before the ondat began scouring the planet.

They were amazed to discover a member of the original First Movement, the Ila, alive after hundreds of years, ruling and spreading her nanoceles.

The Outsiders requested a century to study these nanoceles to see if they could be adapted to reverse contamination here and elsewhere; the ondat gave them 40 years.

The events of Hammerfall followed, where Marak brought many of the locals, including the Ila and her records, to Luz's Refuge before the ondat's hammer fell.

It is revealed that Movement technology was leaked from the planet via the Ila's watcher on Concord and exported to Orb, a nearby station where sophisticated illicits were being manufactured.

Writing in SFRevu, author and academic Edward Carmien (editor of The Cherryh Odyssey) described Forge of Heaven as "immersive, imaginative, and compelling".

[3] A Publishers Weekly review described Forge of Heaven as a "suspenseful sequel to Hammerfall", and called Procyon "[a]mong the many nicely drawn characters" in the book.

[5] In The Cherryh Odyssey science fiction writer and literary critic John Clute described Hammerfall as "an epic, with prose rhythms that evoke the Bible", but added that he had not worked it out, and awaited "the New Testament", the sequel, which he hoped would be "something else".

[6] Clute said that while Forge of Heaven is not quite "the New Testament", it is "queerly and fascinatingly Asimovian" in so far as it is about "the conflict between change and stability", the backbone of Asimov's Foundation and Robot series.