The cover of "Library of Souls" featured a laddie slouched on a pedestal. A pair of owlish wings would spread behind his shoulders. He regarded the camera with quiet contempt. This was the recruiting poster that Jack Peregrine used to gather young peculiars to his cause. It was rooted to his jealousy towards Alma, his sister, who was more talented than him. The siblings were ymbrynes-in-training, but tradition would only allow the females to take the heavy responsibility of taking care of children with special abilities. This was Miss Peregrine's side of the story, which was told in "Miss Peregrine's Home for Peculiar Children". The final chapter of "Hollow City" revealed the transformation of a peregrine falcon into a wight. Jack retained the instinctive traits that kept him connected to his sister, but he preferred to be called Caul.
"Library of Souls", which was published two years ago, revealed the other side of this troubling tale. Bertram Peregrine, younger brother of Jack and Alma, would be the Victorian equivalent of Lord Asriel. His top hat, cane, and gloves turned the older man into a respectable gentleman, who seemed out of place in Devil's Acre. This was the part of London where outcasts lived along peculiars who don't want the likes of Miss Peregrine to tell them what was good for them. Bertram inhabited the Panloopticon, a huge mansion that seemed out of place in Devil's Acre. It was actually a structure with multiple time loops, which Bertram had noble intentions; he wanted to connect with peculiars in other parts of the world, separated and isolated by their fear towards hollowgasts and wights. Jacob Portman and Emma Bloom were too exhausted and too worried to think long and hard about Bertram's vision, where peculiars would unite (and become a force to reckon with). They came to Devil's Acre to save Miss Peregrine and the peculiar kids who lived (with them) in Cairnholm. Power could corrupt anyone. An opportunist who craved for absolute power would be a horrifying thought.
On my own
Most chapters of "Library of Souls" would be devoted to Devil's Acre, which was far from Charles Dickens's description of the slums of London. The road leading to this forsaken place was lined up with shops selling souvenir items, but the shadows behind it was the unlikely location of a time loop.
The romantic depiction of the slums in cinema could deceive moviegoers who haven't set foot in such a place. (For instance, Fernando Meirelles and Kátia Lund used bright colors to show the vibrant side of the favelas in "City of God". The movie depicted the growth of organized crime in that part of Rio de Janeiro, though.) Riggs described a certain street where normals, peculiars, and wights could do "window shopping"; peculiars were on display, and they would show their powers on anyone staring at them. The author might got the idea from Amsterdam's red-light district, which doesn't mean that it doesn't exist in London. This was the heated part of the book, where Jacob argued with Emma and Addison MacHenry about it. Riggs may (or may not) allude to "The American", where Henry James compared the practical-minded Americans and the self-important attitude of Europeans during the turn of the 20th century. But it would be back to fantasy after a chapter or two.
Jacob, Emma, and Addison navigated the narrow streets of Devil's Acre, where inhabitants were ready to pounce on unsuspecting visitors and the forgotten peculiars were hooked to ambrosia. It increased their powers. The wights have unlimited supply, and they needed them for a reason.
This part is not for the faint-hearted readers
The wights chose Devil's Acre as the site of their headquarters, which doesn't mean that they retained some modesty (after the cataclysmic experiment in the summer of 1908). They needed peculiars for their terrifying experiments in a hospital, where they must cut through the least-exposed parts of their bodies.
It was believed that peculiars have two souls. They must go to Abaton to store one soul before their death. This one would contain their special abilities, which were placed inside a jar. The piles of jars resembled an ancient library, which would be invisible to normals and peculiars. Abraham Portman and his (peculiar) descendants could only see it. The tale of Abaton was a myth, but Jack (Caul) thought otherwise. He was intent on domination, and Bertram wanted to prevent it (or so Jack and Emma thought). Readers who idolized Indiana Jones would guess that Abaton was found inside a long-forgotten time loop. Riggs's vernacular photographs revealed humps and spires of red rocks with crude doors and windows. A cavern shaped like a beehive could be found within the structures. It was an ancient city, which might be located in the Middle East. Riggs may be thinking about it for his next trilogy.
Riggs took another sharp turn in "Library of Souls", showing that there would be worse scenarios than wights taunting ymbrynes (after kidnapping peculiar children). The abjectness was hard to fathom in some pages, even drugged (peculiar) kids who don't have a clue about the touristy part of London (outside Devil's Acre). There would be an upside, though. There was more to tell about peculiardom, and three books won't be good enough. (Bertram introduced the grimbears to Jacob and Emma. These furry mammals would protect the peculiars in Russia and Finland.) There was also the possibility of exploring the peculiars in Africa. (The ymbrynes, even Bertram, were in the dark, which would suggest their colonial attitude towards the so-called Dark Continent.) And the extent of Panloopticon. (Jacob and Emma didn't last half an hour in Siberia.)
The final chapter showed Miss Peregrine and the kids deciding to spend a holiday in quiet Florida. Would Miss Peregrine continue her brother's quest (of finding other loops)? Would there be more deserted loops (like Abaton)? Would the remaining wights plan another attack on the ymbrynes and their wards? These questions will be answered in the next trilogy, the first novel coming out this fall. A second compilation of peculiar fairy tales might be included as well.