I stopped reading this at 100 pages and decided to skim the rest in case there was anything good to come. (There wasn't.) By page 100, I was sick of the bad characterization and the constant use of ellipses. (Where in the hell was this "author's" editor? Asleep at the printing press, or the computer screen, apparently.) At page 100, I realized that the "author" didn't know the characters at all. I guess, writing this "novelized fanfiction" stuff might be a "hard sell", especially when it comes to us loyal fans who have been getting to know the characters since day one, episode one. Loyal fans KNOW when a characters is acting out of character. (Sometimes, it's just better to go with actual fanfiction, if you can find any that's more attuned to the show's version of characters.)
As it was, I had a hard enough time focusing on the prologue, which is set in 18-something in the time of Napoleon Bonaparte and a German Grimm named Kessler (where Nick can apparently trace his line), but I kept with it, thinking that it was good to have some background (which we don't really get on the show except via the books kept by Nick's Grimm ancestors). It was okay, it introduced the use of the Coins and Kessler's apparently awful mercy of letting the son of Denswoz, a Wesen (can't recall what kind) live—because this son vowed revenge on all Grimms—after killing the father.
Cut to the present. Or rather, an alternate reality Portland, where Nick is some "super Grimm" who has "magical powers" that are never stated or explored on the show, where he can "sense" when an ordinary looking person is actually Wesen, and "goes red" with that "Grimm instinct" to kill all of any kind of Wesen. (These are quotes or paraphrased quotes from the book.) Not to mention, he's also some rabid borderline serial killer, inventing police related emergencies so he can explore underground tunnels and randomly kill Wesen who might happen to attack. This Nick also insists that Monroe, who might happen to be in the underground tunnel with him and Hank, "woge" and put himself in imminent danger and expose himself to a Wesen-only organized crime syndicate known as "The Icy Touch".... (the ellipses are basically ripped straight from the book, either for "dramatic pause" or just the author's lack of passion for the story-telling, I'm not exactly sure).
Then there's Hank, who, at one point, argues viciously and passionately with Renard about letting the FBI in on the secret world of Wesen, so that "they know what they are dealing with" (because "The Icy Touch" organization is all about Wesen-on-Wesen violence and murder, especially when it comes to those coerced Wesen unwilling to help out when asked so politely). The whole time I was reading this section, I noticed that Nick was eerily silent, except for brief protestations at the beginning of the argument that exposing the Wesen world is unwise.
(The plot is set sometime in Season 2/Season 3, pretty much glossing over the fact that Juliette was in a coma and that Hank got his hasty initiation into the world of Wesen. Juliette also apparently "knows" about Wesen, but she and Nick are not back to being a couple; it's implied they are still living apart and not connected MAINLY because of "Nick's lying to Juliette about his 'Grimm powers'" [again, paraphrasing from the ACTUAL PLOT]. Not even to mention that there's an awkward scene between Nick and Juliette at some cafe again glossing over their disconnection, yet mentioning a necklace that Juliette happens to be wearing, a CAT pendent that Nick apparently gave her because of her "SUCCESSFUL OPERATION OF SAVING A CAT". I'm sorry, but I'm absolutely NOT buying this. At the end of Season 1, Juliette is scratched by Adelind's cat and falls into a coma, where she loses all of her memories of Nick. THERE IS NO WAY IN HELL SHE WOULD HAVE A PENDENT OF A CAT, LET ALONE THAT NICK ACTUALLY GAVE IT TO HER.)
Anyway, back to the Hank-Renard argument. It was absolutely insane and way beyond anything that would ever come out of Hank's mouth regarding the Wesen world. Hank, even still in Season Three, defaults to Nick or even Renard when it comes to how to handle anything Wesen—anything he considers unknown. There's a point in the argument when Hank threatens to resign over Renard's decision to keep the FBI "in the dark" over the whole Wesen/woge thing. That would never happen, at least, not at a point when Hank has barely more than found out about the Wesen world. At that point, he's still pretty freaked out himself, and still thinking himself almost "crazy" for believing in it, so how could he do a complete 180 and try to convince others that it's "all real"? Not buying it.
The absolute last straw for me was the point when Monroe flips out over Rosalee's well-being after an offhand comment from Nick. Instead of calling Rosalee on, say, his cellphone, Monroe runs off dramatically and histrionically in his truck (which, in the show, he doesn't drive a truck, he drives a vintage yellow Beetle looking car) to the spice shop to make certain Rosalee hasn't been attacked by The Icy Touch....
After that, I skimmed the book. At some point, after some early cryptic chapter where Monroe is spying on some fatherless family, the teenage daughter of this family is kidnapped by The Icy Touch.... and then, much later on, Nick is suspended pending an IAB investigation for, likely, his underground tunnel killing spree, and ends up at some bar off the beaten path. He's attacked by Wesen from The Icy Touch... and kidnapped and imprisoned and intended to be killed by a direct descendant of Denswoz (the Wesen that Kessler let live all those many years ago) in some ritual.
Well, that doesn't happen. Nick escapes, Hank and Renard find him, and teenage girl and eventually Nick kills more Wesen. And somewhere after that Juliette starts to warm up to Nick for some reason.
Really, it's a god awful read. The writing itself isn't bad but the characterization is so off that it will make any loyal fan sick. Read at your own risk.