The Tanith First-And Only are among the most legendary regiments of Imperial Guard and at their head stands Commissar Ibram Gaunt, unflinching in duty and unrelenting in combat. The Lost sees the very furure of the regiment in jeopardy as Gaunt battles the forces of Chaos the Sabbat Worlds, from rescue missions to the horrors of the battlefield, the Tanith First-And-Only must survive extreme dangers or be forever lost.