Hi Lorilu1! Marliss' books are great! There is plenty of action and adventure in them. Even more importantly, the characters are very well written. It is so easy to get attached to them. Although each book can stand alone, I highly recommend reading them in order. Some of the same characters are in several of the books and it just makes for more enjoyable reading knowing what they went through in the previous books.
I hope this has helped. I highly recommend Marliss' books. I hope you enjoy them!