See my review of this book, and many more, at Tales from the Great East Road.
(Spoilers for book one.)
After hiding from the world for a few months Alina and Mal are betrayed and handed over to The Darkling, who has not only survived the Shadow Fold but gained a terrifying new power. They travel as prisoners on a pirate ship across the True Sea, hunting and capturing the mythical ice dragon known as the Sea Whip, to use its scales as another amplifier. The Darkling's disturbing new plan to control both Alina and the Shadow Fold nearly comes into fruition - until the Captain, Sturmhond, steals the Sea Whip and escapes with both Alina and Mal across the Shadow Fold and back to Ravka.
After only just surviving an attack on the Fold, Strumhond reveals his true identity and his plans to fight against The Darkling, but he needs Alina's help. Taken back to the Little Palace, Alina struggles to juggle uniting and leading the other Grishas, play politics with the Royal Family, dealing with the public belief that she is a Saint, and keep her relationship with Mal from falling apart. When she discovers that there is a third and final mythical creature that can be used as an amplifier, Alina has to face whether her desire for this power is just her duty to defeat The Darkling, or for her own gain.
If Shadow and Bone begins the series in with a familiar fantasy story, Siege and Storm throws out these well known and used ideas, and carves out its own path in a completely unpredictable way. It's a thrilling book, full of surprising twists that work to make a brilliantly entertaining and clever read. One of the main causes of these twist is the character Strumhond, the notorious privateer who is not who everyone believes him to be. With a reputation for being charmingly clever as well as a cut-throat, he and his ship are for hire to the highest bidder - but you can never trust that you are in fact the highest bidder. Brilliantly scheming, charmingly witting, and a naturally confidant leader, Shurmhond is a new favourite character.
This book not easy on its treatment of Alina. She is struggling to fight a war and accept her responsibilities as the Sun Summoner by embracing her power whilst trying to still remain herself, despite finding that she is becoming increasingly tempted by the idea of more. She is terrified of turning into a monster, like The Darkling, but can't stop herself thinking about him, and though she denies it, she is beginning to relate to him. Alina also has to deal with the expectations of the public believing her to be a Saint, the weight of her duty to save Ravka and being "holy" slowly crushing her spirit, but not her determination. Alina is a wonderfully written character, becoming even more real in this book. Her strength is admirable and her inner conflicts make her a relatable character, and just like the plot she makes some surprising but great choices.
The only setback to Siege and Storm was the ongoing relationship drama between Alina and Mal, mainly caused by Mal's stubborn belief that Alina thinks her power makes her better than him. Whilst the reader can see through Alina's narrative that this not true, it is obvious that her power does drive a wedge between them. This gives Alina another complication with obtaining the last amplifier, as she will have to eventually choose between her power and Mal. Mal, however, comes across as fairly selfish because of this and becomes just one more person demanding something from Alina.
It's impossible to to predict where the next book, Ruin and Rising, will go, but I personally cannot wait to see what will happen. My only complaint is that the next book is sadly the last. This series is highly recommended.