'The summoning' story arc continues here and the Grimm Universe will never be the same. With all three pieces of the amulet finally brought together the key gem is the final item missing needed in order to summon Helios from his eternal prison. Using the shards Baba Yaga, the Sea Witch and Venus track down the Innocent who holds the key. The only thing standing between them and world domination is Samantha and things are not looking good for the guardian of the nexus.