Grey Hunter

Ragnar Blackmane and the Space Wolves are en route to the sacred world of Garm in search of one of the Chapter's most sacred relics when they are attacked by a huge Chaos fleet.
The enraged Space Wolves learn that there is more to the attack than they could have guessed, and that they must quell this Chaos incursion before one of the Chapter's biggest foes is reborn.

Read it because
It's the tale of one of the defining events in the life of Ragnar Blackmane, and a thrilling continuation of the ten millennia-long battle between the Space Wolves and the Thousand Sons.