The House is being destroyed -- it's being flooded with Nothing and invaded by Newniths.
So it's not exactly surprising that the final novel of Garth Nix's multiverse-spanning Keys to the Kingdom series is one long cliffhanger. "Lord Sunday" is a little rushed and scattered at times, but Nix ties off the various plot threads in a satisfying manner -- and he demonstrates his brilliant skill by handling the seemingly impossible.
Now transformed into a Denizen, Arthur struggles his way back to the Incomparable Gardens -- only to be captured by the cruel, selfish Lord Sunday and his minions. Meanwhile, Leaf is captured by Sunday's Reaper and dragged back into the House, and Suzy is struggling to keep Arthur's army from being destroyed by the Nothing, Newniths and the Piper's Children.
Unsurprisingly, Lord Sunday wants the Atlas and the Keys. Arthur will have to use all his wits and sorcerous strength -- as well as an old, beloved friend -- to free himself from Sunday's clocklike torture chamber. As the final clash between Sunday, Saturday and the Piper begins, Arthur's true destiny is revealed -- and it may mean the destruction of all the worlds of the House.
"Lord Sunday" has almost everything you could want in a grand, apocalyptic finale -- magic, battles, tragic losses, and finally the revelation of the Architect's true Will. It took six books of complex build-ups to get to this point, and most of the book Nix focuses on the main characters zipping around trying to save the House from destruction.
And Nix packs the novel with plenty of gritty action (including Arthur getting part of his head blown off), world-hopping, and some beautifully poignant moments (Arthur telling his elephant that it's all he has to remind him "who I really am"). Problems? The titular Lord Sunday isn't much of a character (he's more of a one-off obstacle), and a really tragic loss for Arthur is handled almost as an afterthought.
But it becomes truly exquisite in the last few chapters -- Nix weaves in some brilliant philosophical moments that reveal why the Architect did all this, and why Arthur was necessary. It's a rather bittersweet ending for the series, but also leaves you feeling hopeful.
And of course, Arthur is still the center of the story. While Leaf, Suzy and a few other characters (including the adorable Elephant and the beastwort Daisy) get moments to shine, "Lord Sunday" is about taking Arthur to the end of his journey, and dealing with the divide between his Denizen body and human heart. Without revealing too much, Nix handles it in a logical, fantastical way that just makes sense.
"Lord Sunday" has a few flaws here and there, but it is a truly brilliant, powerful wrap-up for Garth Nix's epic fantasy series. Hopeful, sad, and hauntingly lovely.