Samantha Shannon has kept fans waiting two years for the fourth installment of her The Bone Season series, The Mask Falling, but it’s certainly worth the wait.

Note: If you haven’t read the other three books, read on at your own risk – potential spoilers.

This chapter of Shannon’s saga picks up immediately where the previous left off. Having wreaked utter havoc – or devastation depending on how you look at it – on Rephaim plans to further tighten the Scion control over voyants, The Mask Falling begins with the reader finding Paige, badly injured by her captors, smuggled to a safe house in Paris – in the Scion Citadel to be precise. As with many good deeds, she soon learns that the Domino Program, who have taken her in, want something in exchange for their kindness, but they’re not the only ones with an agenda – the “new” Underqueen – a position Paige has all but lost – does too.

Paige knows that if the syndicates of England and France united, the growing tide of rebellion could indeed become an all-out war. A victim of the rebellion itself, Paige finds herself struggling to convince the Parisian underworld to back her plan, while at the same time struggling with her own mental, emotional and physical pain, as the Scion broaden their reach and their hold over several countries in Europe. She does however continue to find strength and support through her albeit complicated bond with Arcturus Mesarthim, even if the growing number of enemies she finds herself going up against are doing all they can to break them apart. The two of them began the rebellion – removing them from the equation, so to speak, could end it.

The Mask Falling is perhaps the most complex of the books in this series so far. Yes, ultimately it focuses on and is about Paige, but there’s so much more to it. The voyant aspect of the story – they struggle to survive because much of the world they live in hate them for just being who they are – can be related in modern day terms to migrants and the millions of refugees that so many people dislike because they’re not “like them” and because of where they’ve come from. With each book, the lines between who is an ally and who is an enemy have somewhat blurred, or been destroyed completely, and this works to serve as a reminder that there is no such simple thing as good and evil; there are many grey areas to people, society and the world as a whole, and it all makes for a very complicated existence.

The other strong aspect of this book, which this reviewer in particular found to be hugely important, is its addressing of mental health issues. With book four, everything Paige has endured has occurred in the space of a year. She’s suffered betrayal, torment, loss and seen her world and life change on an all but imaginable scale. Paige, as do several other characters featured in the book, display classic signs of PTSD and it is in The Mask Falling that Paige finally admits to herself that she can no longer ‘carry’ the burdens she has because of her recent experiences.

PTSD and other mental health issues can be tricky to write about and if not done properly, can make the conditions come across as unimportant, when they are in fact exactly the opposite. Shannon handles Paige’s mental health in particular with compassion and consideration, perhaps all to aware that many of her readers will find themselves identifying with the struggles the protagonist of the story is going through. Paige is after all just a girl – not a superhero or mythical, unbreakable being incapable of being hurt – trying to survive, and the rawness with which that fact is expressed and detailed through the pages is impressive and powerful. Several other characters in the book are seen to cope with their struggles in their own way, highlighting how no one ‘coping’ mechanism fits all, and how many of the decisions characters make are and can be influenced by – as happens with everyone – their thoughts, feelings and experiences.

The book also introduces an aspect or consideration of and for forgiveness, something much lacking in the other books, but rightly so, given the story. The way this plays out makes the reader ask questions: Can the mistakes of the past ever be rectified? Does everyone deserve forgiveness? It’s an interesting, exciting dynamic of sorts and one I certainly haven’t seen in a book for some time.

Ultimately, The Mask Falling takes the previous three books and expands everything that features in them ten-fold. There’s stronger, brighter, fresher perspectives – not just from Paige but other characters too – and more depth; physical, emotional and mental. The book is a testament to Shannon’s writing prowess and solidifies her place as one of the best fantasy writers of our time. Where she’ll take the reader next is an exciting – thrilling – thought.

The Mask Falling is out now and available online and in bookshops.