Romantic suspense runs on a simple engine: danger pushes two people together, then does its best to prise them apart. Nyssa Kathryn works that engine cleanly. Whispers in the Water belongs to the Deep River strand, where the threat is specific and the romance is never an afterthought bolted on at the end.
The writing favours momentum. Chapters finish where they should, tension is renewed rather than simply repeated, and the protective instinct driving this subgenre is played straight instead of ironically. It is comfort listening in the way a well-built thriller is comfort listening: you trust the author to land it.