From Lexicanum

A Thousand Sons by Graham McNeill will be the twelfth novel in the Horus Heresy Series. A number of authors contribute to the series, but the storyline follows the same characters through Horus' descent into Chaos.

The novel is scheduled for publication in March 2010.

Plot Summary

Censured at the Council of Nikaea for his flagrant use of sorcery, Magnus the Red and his Thousand Sons Legion retreat to their homeworld of Prospero to continue their use of the arcane arts in secret. But when the ill–fated primarch forsees the treachery of Warmaster Horus and warns the Emperor with the very powers he was forbidden to use, the Master of Mankind dispatches fellow primarch Leman Russ to attack Prospero itself. But Magnus has seen more than the betrayal of Horus and the witnessed revelations will change the fate of his fallen Legion, and its primarch, forever.