Rosa Ramona Díaz's mom is a librarian who specializes in ghost-appeasement--a valuable skill in a world where ghosts are ubiquitous, and libraries are dense with spirits. But her mom has taken a job in the small town of Ingot, the only town in the world that's utterly unhaunted, and she absolutely does not want to be there. For one thing, she'll have no chance to practice her own ghost appeasement efforts. Given the choice about being sad about her father's recent death (he was also a ghost appeaser, but bad at it) and being angry about being stuck in a basement apartment below an unhaunted library, she choses to be angry.
Then she meets Jasper, who's always lived in Ingot, and whose father is a knight at the local Renaissance Festival, where his mother plays the queen. Jasper, his father's squire, has never seen a ghost, but this changes suddenly when the Renaissance Festival is attached by angry spirits. Rosa's ghost-appeasing and containing skills come in handy, but she can't cope with the sudden influx of ghostly mayhem. Even her mother is not strong enough to face the onslaught, and a ferociously powerful ghost steals her voice.
Now Rosa and Jasper must race to find out why there is a barrier around Ingot that keeps the ghosts away, and why it starting to fail. If the ghosts break through all the way, it will be a catastrophe. But if the balance between the living and the dead can be restored before that happens, Ingot will be properly haunted, just like the rest of the world, and disaster will be averted. The mystery lies deep in Ingot's past (and its "passed"--pun intended), and will require all Rosa and Jasper's courage and perseverance to solve it and to lay a dark past to rest.
It is a short book, by the doorstopper standards of much middle grade fantasy (adding to its suitability for the younger middle grade set), and it is a book that doesn't spell everything out. For instance, there's an environmental disaster entwined with ghost problem (copper mining), that's alluded to but not underlined. Rosa's grief for her father is a key part of her character and her choices, but again (partly because Rosa tries to squash it), isn't made a focus of the story. Her grief ties to the larger message that underlies the whole story that the past, with its sadness, should be accepted, and that desperate efforts to banish ghosts and memories bring more harm than good. That being said, some things are made obvious to the reader, and add lots to texture of the story, like Jasper's black father being a Moorish knight, bringing diversity to the Renaissance portrayed in the town's festival.
In short: a gripping, engaging mystery/fantasy with diverse characters set in a fascinating alternate reality.
And now I treat myself to reading the Kirkus review (starred) and find I am in total agreement:
"Though it’s a perfectly enjoyable tale on a purely superficial level, readers who choose to dig deeper will find an engrossing exploration of complicated grief and what damage may be wrought when negative emotions are barricaded away rather than addressed. A fun and fast-paced supernatural mystery with secret depths for those who dare explore them."
Final thought-- a special yay for a book that gives black kids the chance to see themselves as part of medieval pageantry!