Enemy in Shadows Companion includes:

Exclusive insight and commentary from Warhammer Legends Graeme Davis and Phil Gallagher.
The Empire: a look at the foremost power of the Old World, its politics and influence.
Travel in the Empire: road travel, mounts, vehicles, and the hardy Road Wardens who struggle to keep the byways of the Empire open.
A plethora of new NPCs to aid, hunt, frustrate, and scoff at your players.
The Purple Hand: An in-depth look at that most insidious of cults, including a full new Career, The Cult Magus of Tzeentch.
25 new Chaos spells for the mad, the desperate, and those unafraid to wield true power.
Three classic encounters, including the beastly Pandemonium Carnival and its terrible menagerie of monsters, not all of whom are caged.
The classic adventure The Affair of the Hidden Jewel, a dramatic tale of heroics and intrigue with fully updated rules.