This is probably my least favourite of the trilogy, though it’s partly down to personal taste: I didn’t enjoy the characters or their dynamic as much. Nathaniel is pretty awesome in his unthinking protectiveness and willingness to help others, but Justin mostly just ticked me off. He does have some redeeming features (particularly his relationship with the kids he looks after), but I still didn’t quite get that relationship.
It’s useful for piecing together the full story begun in An Unseen Attraction (or An Unsuitable Heir if you started with that, like I did!) but it’s not necessary, and personally, I wouldn’t have minded giving it a miss. It’s not a bad story, and there certainly is intensity between the main couple, but they just weren’t the type of characters I really root for.