Captain Sebastian Alexander is the "spare", meaning that as the youngest son, he's the spare in case something happens to either one of his older brothers -- which does.  His older brother died  ten years ago; but it is when his middle brother, Andrew, dies that  Sebastian becomes the heir to Pennhyll.  Now he must do his duty: marry and sire an heir.  So, he chooses his friend's sister, Diana, hoping that once his duty is complete, she will just leave him alone.  However, he discovers that Diana's friend, Olivia, is a far more interesting target.  See, he's investigating the death of his brother and  believes Olivia holds the key.  He will do whatever he has to to find out what happened on that day.  The only hitch to his plans is that Olivia doesn't remember anything of that day and Sebastian is besotted with her!  Discovering the truth might be harder than either one of them thought!

Sebastian was a character I grew to like a lot.  He was obsessed with discovering what happened to his brother, even at the expense of hurting Olivia.  As he got to know her, his feelings grew stronger and he realized that she had a lot to deal with herself.  The amnesia plot got tiring after a while, but it made for an interesting ending.  Olivia was a strong heroine, facing near impossible odds to sort out her past and her future.  This was a book that distracted me a bit with some of the scenes - as I didn't know if they were really happening or not.  Since this was the author's intention, I'm sure, she did a good job of keeping my interest!