"Tristan's Gap" is a Christian general fiction book. While the book was from a woman's point of view, the issues were mainly about parenting in general, so men might enjoy it as well.
The characters were varied, acted in realistic ways, and dealt with realistic issues. The suspense was created by relationship tensions, not knowing what happened to Tristan and some instances where Serena was in physical danger. The unique setting details brought the story alive in my imagination.
I did wonder why the detective didn't just check the phone records to see where the phone call came from. It would have cut several months off the search. However, it's a minor point.
The Christian element was woven into the story and flowed as a natural part of the story. There were some short conversations about God, but they didn't give "easy answers" to Serena's questions and didn't come across as sermons to the reader.
There were no sex scenes. There was a minor amount of fake bad language. Overall, I'd recommend this book.