I've read and liked the two books of the series so I read this novella, too; all the better that it focused on Konstantin, an interesting character who could have more adventures on his own.
I knew there was going to be romance and it was fine, the series had a nice balance, but the story here is just a backdrop for the romance, and a dull one at that.
Both the protagonists behave either stiffly or as giddy teenagers and there is neither tension nor intensity. The story has too many gaps and contrived plot devices (like, where is the strict Russian surveillance since Himmel and Konstantin are allowed to go traipsing as they please? Or what's with the friendly guard dog? And how come Konstantin was fired but nobody notified his team? And what about unattended diesel pumps in the middle of nowhere at the right moment? Not to mention masquerades. Oh, whatever.), it's predictable and not convincing.
The ending was consistent with the boring ride. I could have safely skipped this one, it adds nothing to the series.“Why did you decide to tell me tonight?” “Because this might be my only shot.”