The City in the Middle of the Night

The book was introduced to me as an example of a setting on a tidally locked planet. Well it was set on a tidally locked planet, but it was utterly incidental, irrelevant to the plot and hardly explored. The book is technically sci-fi, but it could just as well have been written as fantasy, and it wouldn't have changed a thing. And all of it would have been fine if I just could connect with the characters or felt invested in the story.