"Kirk? The man was a menace" is one of the first emotional statements we hear from a DTI-agent in the DS9-Tribble-episode. These "Men in Gray" fitting to Ende's "Momo" don't like people flitting around the timescape and the dimensions and Cpt. Kirk holds the sole record in doing exactly that in the space of influence of the DTI. But why does he and his crew get into situations like this more often than other StarFleet-crews. Among other things, this book tries to give an explanation to this.
Apart from this, we can read a lot about his "transgressions" from the perspective of the DTI and how the latter has been first formed and then again and again repurposed following incidents concerning the ENTERPRISE. And a new case in which the old warp-drive of Kirk's first ENTERPRISE is involved brings the initially mentioned agent face to face with his sworn enemy.
"Historically" quite interesting but the rehashing of Kirk's time- and dimensiontravels gets a bit old the perceived 2.000th time around and the incident at the core of this book is quite strained as a especially strange Dr. Who-episode. Here 50 pages less all in all would have been a good thing. But as I said - the "history" of the DTI is interesting.