While most fans had to wait two years for book six of the Mortal Instruments series to be released, I only got on the bandwagon a few months ago, so I've been lucky. Still, the fifth book ended with more cliffhangers than most, so it wasn't an easy wait.
City of Lost Souls left off with Sebastian's plan to create a race of evil Shadowhunters thwarted for the time being. However, Jace now possessed the uncontrollable heavenly fire inside him, Simon had lost his invulnerability and Alec had just found himself at the mercy of the ruthless vampire Maureen right after Magnus broke up with him. Clary at least, was doing relatively well, all things considered.
City of Heavenly Fire doesn't immediately address many of the questions the readers were left with as there are some other horrors to get out of the way first: Sebastian has started gathering his dark army after all. But pretty soon we're back in familiar territory (some questions brushed off a little too easily I thought) with all the main characters, as well as some new ones, rallying to prepare for the war that is coming and fighting to have their warnings heard by the adults in charge. It's a recurring theme in young adult fiction, but something Clare playfully acknowledges at one stage through Jace.
The scope of City of Heavenly Fire is grand when you think about it, with Shadowhunters around the world directly affected, as well as all the Downworlder races. There's even the introduction of a new key family: the Blackthorns. But even with all of these different strands, Clare has made it all feel so intimate.
Clary and Jace are finally safe in their love, with moments that actually made me smile (easier now the aura of incest is gone) though Jace still needs to sort out how to control the heavenly fire. It's Alec and Magnus who are having the biggest problems. And of course Isabelle and Simon, and Maia and Jordan too. They're all at their rawest and best yet.
For me, City of Heavenly Fire perfectly carried on the story that the Mortal Instruments series has carried over the course of its run. In fact, these novels have to be some of the most cohesive I've ever read, as they hardly seem like individual books, just one extremely long one (this one is particularly thick, but will be devoured quickly I assure you).
At the same time however, Mortal Instruments isn't a stand-alone series. Clare has two other trilogies, The Infernal Devices prequels and The Dark Artifices (not yet released) and references to the stories and characters of these other novels have been woven into City of Heavenly Fire more obviously than I remember in the other books, such as Brother Zachariah's past.
Not having read even the prequel series yet, I don't know these other characters or their histories, so I would have preferred Clare just stick to the Mortal Instruments story and the characters I've become attached to in this series (and there's certainly enough of them). She's clearly doing a bit of promotion for them, particularly in laying the groundwork for the next series. But I guess it's all served its purpose, as now I feel like I should go and read them too.