A large, tripedal, religiously zealous alien species waging a galaxy-wide war against the Culture. The Idirans believe their God has granted them dominion over all lesser species, and they view the Culture's machine-led civilisation as an abomination. Despite their fanaticism, they are formidable warriors and strategic thinkers.

A small mercenary free-company ship captained by Kraiklyn, operating on the fringes of the Idiran-Culture war. Its crew are a motley collection of opportunists, outcasts, and those with nowhere better to be.