The second book in the Thorn of Breland series picks up the next adventure of secret agent Thorn, one of the Dark Lanterns of Breland. Set in Eberron, and written by the setting's creator, Keith Baker, it once again delves into one of the adventure seeds from the setting which had not been largely addressed beyond the basic references in the setting books for the game. This time, Thorn is sent to investigate the thief/assassin's guild known as House Tarkanan. Unlike a typical guild, this group has a core political agenda of rights for those who develop aberrant dragonmarks, and are persecuted by the twelve great dragonmarked houses (like a fantasy version of a global megacorporation) for being dangerous to the established order, as their magical marks don't fit the patterns the houses have established, and "cause those with them to go mad".
Thorn is sent to investigate a new leader of the Tarkanans, the titular Son of Khyber, who seems to be moving the group towards more dangerous acts that could destabilize the kingdom, rather than as just another petty crime group. As she infiltrates the group and gains access to it's inner circle, her loyalties are put to the test, as her own nature is questioned - is she like the Tarkanans and some sort of magical outcast? Is she really doing the work of the kingdom of Breland, or has her agency, the Dark Lanterns succumbed to influence of the Twelve Houses to do their dirty work for them. The seeds from the first book about whatever strangeness is going on in her psyche is a far more prevalent plot point in this book, and seems to be set up as the meta-plot that binds each of the books in the trilogy together.
Overall, the book was enjoyable, but seemed a bit forced - it becomes more and more clear that her handlers in the Dark Lanterns know far more about what's going on with Thorn than they've told her, and things are set up where she simply can't address them, which seems contrived. Once assigned her mission, despite her doubts about it on several fronts, she seems to have no way to find out information, except what she's told by the target of her mission, and the cryptic dreams she has. I'd expect a skilled agent to have contacts in a major city, or be able to track down wizards, psions, sages, or others to independently figure out what's going on.
Also, while the book does illuminate the House Tarkanan and how it fits into the overall Eberron setting far better than any other Eberron game product or book to date, it's ended without really advancing their plotline, and feels like more should happen with them.....but the final book of the series doesn't seem to be about them at all, so this plot ends on a somewhat unsatisfactory note.