Luna Mendax (The Horus Heresy Series)

Returning from a secretive mission to Caliban at the command of Malcador the Sigillite, the Knight Errant Garviel Loken finds sanctuary in one of the abandoned bio-domes of Luna. Scarred by betrayal and bewildered by the changing face of the galaxy, the weary warrior is almost unsurprised when he is visited by the long-dead Tarik Torgaddon – is this a sign of a fractured and exhausted mind playing tricks on itself, or truly the spirit of a departed friend?

Read it because
It's a fascinating look at the fractured psyche of everyone's favourite Luna Wolf, and is packed with hints as to the true nature of Chaos and the trials that Loken will face as his future unfolds.