||This article is about the the short-story, for the xeno-species see Cryptos
Kryptos is a short story by Graham McNeill in the Horus Heresy series, published online in June, 2012.
Bloodied but unbowed, the Raven Guard and the Iron Hands fight on. In the wake of the Dropsite Massacre, the shattered Legions are still prepared to bring the fight to Warmaster Horus and his traitorous allies. On the doomed forge world of Cavor Sarta, two veteran warriors of the Imperium strike deep into the heart of the Dark Mechanicum’s territory. With bolter and blade ready to cut down any who cross their path, they will seek out the enemy’s most valued asset: the mysterious ‘Kryptos’...
1: Black Library page for Kryptos