Graham McNeill’s Horus Heresy novel Vengeful Spirit spun together a huge number of character threads, some of which were left crying out to be followed up in later stories. With Wolf Mother, McNeill picks up a few of those characters in the immediate wake of Vengeful Spirit’s conclusion, focusing on Alivia Sureka as she is forced to work alongside the Knight Errant Severian in order to rescue her adopted daughter from a resurgent fragment of Molech’s Serpent Cult.