The Neutronium Alchemist is the second book in The Night's Dawn Trilogy by Peter F. Hamilton, the first being The Reality Dysfunction and the third being The Naked God. It was published in 1997; in the US, it was broken into two volumes, Consolidation and Conflict. This novel, along with others in the series, is noted for its long-windedness (>1000 pages long) and technological depth.
Also operating parallel is the story of Alkad Mzu who escaped via blackhawk in the previous novels. Her quest to recover the Alchemist operates as a mostly separate storyline, with the possession crisis mainly operating as a background from which the action takes place.