Following directly in the wake of The Temple of Yellow Skulls, our heroes face the totality of the destructive and pestilent forces presented by the Abyssal Plague. The disease of the liquid crystal Voidharrow spreads throughout the land, transforming unsuspecting creatures into plague demons.
Shara, Uldane, and the unlikely drow hero Valmaggar join forces with Tempest and Rohgar from The Mark of Nerath, and together they set out in search of the green dragon Vestapalk, or the creature Vestapalk has become - the patient zero of this abyssal plague.
Meanwhile, Albanon and the mysterious cleric Kri Redshal - the last remaining member of the Order of Vigilance, an order dedicated to guarding the Voidharrow - go in search of answers to the disease that sweeps the land. While their search takes them deep into the heart of the darkness that is enveloping the land, the answers they find are truly in need of new questions. As they become aware of the true scale of the tragedy at hand, they see the forces behind them are more powerful than they had ever dreamed, and perhaps more seductive.