The book I read was The Avenger by P.C. Cast which is a favorite author of mine. This is the 3rd book in the series but they do stand alone. The only one that will not stand alone will be the last book since it will be using all the pieces from the other books. The book starts with a lady named Alex who can see ghosts and hats it. It has made her life miserable and she has found a place where not many ghosts go and does not want to leave. She also used to be in the army. The Government has asked her to come back and help them with one more mission. The mission is to travel back in time to 60 AD and to locate a important piece that will help the future earth against an alien race that has decided they do not like the human race and plans on destroying it. Of course when she gets there she falls madly in love with the Druid who helps her.
I believe that all the books are little romances with a strong female character who will find their perfect mate while doing whatever mission they are on. If you like romances and scifi you will probably like these books. For now I have only read the one but I will probably read the others.