This is book four of the Whispering Mountain series but can be read stand alone.
The other books are:
Book 1 Texas Rain (Travis and Rainey)
Book 2 Texas Princess (Tobin and Liberty)
Book 3 Tall, Dark Texan (Teagen and Jessie)
Book 4 The Lone Texan (Sage and Drummond)
Travis, Tobin, Teagen are brothers and Sage is their younger sister. I have only read Teagen's story prior to reading the Lone Texan. Drummond has had Sage in his sights since he first met her. He is younger than her by about 3 years (which is refreshing after reading some Diana Palmer novels). Sage has just returned from studying back east to be a doctor. She is accompanied by her assistant (a nurse) Bonnie. The romance between Bonnie and Brad(ford) is almost as good as between the main characters. Drummond Roak is both gunfighter and pure alpha, and he wants Sage "as is", doesn't want to change her at all, a true partner. Sage has 3 older protective brothers and being a woman in the "old west" mistrusts marriage and ever being a "little woman". As she is older than Drum she has viewed him as "the kid", meeting him again as a man, and then coming to view him as he views her makes for a very good story.
I will be purchasing books 1 and 2 and there is a new "whispering mountain" book out, Texas Blue, but I am not sure how that one connect to the ones I've already read.