Robbie MacNiven - The Young Wolf's Return (Legacy of Russ, Book 2)

As the Fenris System is beset on all fronts by a vast daemonic incursion, the Space Wolves fight with redoubled savagery and heroism. A conflict of such magnitude cannot remain unnoticed by the wider Imperium however, and over a dozen other Space Marine Chapters, the Dark Angels foremost amongst them, stand ready to enforce the ultimate sanction against those planets drowning under the endless waves of warp-spawn. Worse, the Great Wolf himself, Logan Grimnar, is still missing. Will salvation arrive in time for the Sons of Russ, or will their Chapter suffer a blow from which they might never recover?
Read it because
Ten millennia of enmity between the Space Wolves and the Dark Angels comes to this: the fate of Fenris and the sons of Russ might lie in the hands of the children of the Lion. What will happen? We can barely begin to guess.