This is Brian Staveley's first book. It is ... long-winded. Amazon claims it's 500 pages in paperback form - it felt longer than that. This is also the first book of a trilogy: the ending brings some closure, but mostly indicates that things are about to get worse.
Our protagonists are the three children of the emperor, each receiving their own unusual training. The threat is the death of their father, and the country-wide plot against their entire family. Kaden is the heir to the throne, who has spent eight years training as a monk (with good reason, as we eventually find out). His sister Adare has remained in the capital, where their father has recently raised her to the position of Minister of Finance. Their younger brother Valyn has been training as a warrior, one of the elite Kettral.
The book moves back and forth between these three perspectives. Adare, despite being in the capital, is the second-class citizen: most of the book is about the brutal (and very different) training the two brothers are receiving. In fact, what we mostly learn about Adare is that she cannot, under any circumstances, hold her tongue if she's upset (not an ideal trait for a politician). Her brothers have tempers on them too, although Kaden's has been tempered by his training. But every mystery, every problem, is drawn out over pages and pages of detail. This could be appealing if the writing was great, but Stavely doesn't have the skill for it (yet). His plotting is fairly good, the plots and politics across two continents are reasonably well played. And the prose is passable. But his characters ... Adare's only real character trait is her inability to control herself ... right up until the end of the book when she manages a very sudden complete reversal. And Valyn likewise is almost always unable to control himself. Sure, I get it's a family trait (but we never heard about it from their mother or father, and that seems unlikely). His rage is used as a plot device to put him into worse and worse predicaments, when even he knows if he'd just controlled it ... Kaden in the mean time is receiving an training that's fairly opaque: he doesn't know what the point is, and neither do we, so it just looks like 500 pages of torture.
A really good writer throws meaningless details into a story to add flavour. A competent writer gives you exactly the amount of detail that you need and no more. An incompetent writer throws in unnecessary details either because they're plot points they meant to develop later but didn't, or just because they got distracted. Staveley is competent, but the problem with competence is when you're sitting there thinking "that was an utterly bizarre non sequitur ... oh, he's prepping us for later."
There are some appealing features to Staveley's writing: he's fairly inventive and it was NOT predictable (one of the worst crimes in my world is predictable plot points), but I was deeply frustrated by how much he drew out every plot point and by how consistently bone-headed his main characters were. The prose and the plot both lacked ... elegance.