The Black Song picks up where the previous book left off, as the Darkblade, leader of a barbarian people known as the Stahlhast and, more recently, a self-proclaimed god, is sweeping across the realm, converting throngs of people into rabidly devout followers and killing the rest. As he leaves a trail of destruction behind him, his ranks swell in numbers, making him a very dangerous foe, indeed. In addition, he actively harvests the magically gifted children among his new devout followers, keeping them close and training them to be his own super-powered special ops force.
A force like that can't be simply defeated directly. Vaelin will have to use every trick and advantage he can get. Luckily, his "song," a magical sense that provides insight into the world around him, helps to guide him in what is needed to defeat the Darkblade. Unfortunately, this same song threatens to take over when he's in the thick of a fight. When it does, he will fight viciously and sadistically, leaving behind a scene of wanton torture and destruction that's not for the faint of constitution. Vaelin will need to maintain control over himself and his black song, while focusing on achieving an edge over the Darkblade in time to defeat him.
His journey to prepare for the upcoming confrontation with the Darkblade leads Vaelin to the Temple of Spears, a strange ancient temple whose inhabitants don't worship at the temple or worship the temple, so much as do the will of the temple. As the abbot says, "The Temple of Spears is a living thing. It does not belong to my order; we belong to it."
Vaelin was hoping to meet back up with some of his friends and compatriots, but he arrives to find that they've already left. Fighting to maintain control of his song has left him quite strung out, but he finds a temporary respite from the black song within the temple walls. However, the order requires him to overcome a series of five tests to secure the temple's assistance - and refuses to allow him to leave until he does so. Without the assistance of the Temple of Spears, all might be lost. If he completes the trials, the abbot says the temple can provide something to keep his black song's aggression under control. However, time is of the essence, and the trials can require years for some to overcome.
The search for some form of advantage pushes Vaelin to take a seafaring voyage to an uncharted realm, directed by his song in an attempt to find a mystical stone with properties that he hopes... somehow... will stop the Darkblade.
Each section in the book starts with a chapter called "Obvar's Account" and fills in what's been happening in the Darkblade's camp, as told by Obvar, the Darkblade's most trusted General or favorite dog, as Obvar sees it. Obvar was a friend of the Darkblade's growing up, when he was just Kehlbrand Reyerik, before his rise as the Darkblade. But that was in a previous life. Now, Obvar finds himself more and more disgusted by the Darkblade's actions. He is not the man he once was and this leads to increasing resentment and conflict between them, which could work to Vaelin's favor.
I enjoyed The Black Song a good bit. The adventure is action-packed and interesting, although the path seems a bit circuitous at times, with the black song providing an all-too-convenient reason for advancing the plot in any given direction. I was sorry to realize that this was the last book in the duology; I look forward to reading more of Vaelin's adventures. Perhaps I need to read some of Anthony Ryan's earlier works, as Vaelin Al Sorna is an existing character from other of Anthony Ryan's books. I did read on Anthony Ryan's website that he is planning to add to the continuing adventures of Vaelin Al Sorna, though not in the near future.