Melvin Burgess 
Bloodtide 

PART I London is in ruins, a once highly advanced city now a gated wasteland. Within its walls, a bloody war rages between two clans. Hope is sparse, but the people believe the gods have risen from the dead. Odin himself has come to play a part in the lives of two twins, a brother and sister from the Volson clan. Siggy and Signy must come to grips with their destiny as London’s future teeters on the edge of a knife….