4.5 stars, for sure.

For all his vaunted intelligence (he is a Holmes, after all), Mycroft is still given to the follies of youth. He is aware of them, of course, but dismisses any problems his arrogance might cause until it catches up to him. Cyrus Douglas, his best friend, is an older man who indulges Mycroft's need for adulation for while keeping his own counsel on Mycroft's naiveté. It's a shifting of the traditional Sherlock and Watson dynamic. We don't need two pairs of the exact same characters running about, after all.

In Trinidad, there is a lougarou terrorizing the people and Mycroft is going to get to the bottom of it - if only because the disappearances of the island natives is causing emotional distress to Douglas (an ex-pat) and his fiancée Georgiana, with whom he is thoroughly twitterpatted. He manipulates his boss, the Secretary of State for War, into sending him there to prevent an (entirely exaggerated) incipent revolt just to pursue this investigation.

A baby student Sherlock shows up briefly before Mycroft leaves for Trinidad. I got unreasonably excited at this interaction. Mycroft schools him on "allowing [his] feelings to get in the way of [his] deductions" regarding an old case Sherlock was pondering over. Immediately after they box while Mycroft needles him into deducing why he came to visit Sherlock in the first place. You can very clearly see the roads the authors are laying about Mycroft's influence on Sherlock's older, canonical personality.

"You are insufferable."
"So I've been told," Sherlock said, "more times than I care to recall. Though I do, unhappily, recall each time."

Very quickly, the mystery of the lougarou becomes the mystery of Georgiana. It is apparent that she's keeping secrets, secrets that lead to a near fatal poisoning and then a severe beating for both of our intrepid heroes. As Mycroft unravels the thread of her story, he becomes more and more despondent as he realizes that he never knew Georgiana at all. She is The Woman to Mycroft, as damaging to his emotional state of being as Irene Adler will be to Sherlock's ego. This experience, both with Georgiana and the hardships he endures while in Trinidad, hardens his heart exponentially.

Basically, this was a delight and a half to read despite the increasingly heavy subject matter. I would absolutely love a sequel, with more of Mycroft and Douglas' adventures in politics and intrigue.