Overall I liked this book, which is good because for some reason I decided to already buy the rest of the books when they were discounted sometime earlier.
The book opens with a mysterious pair who have landed in 1912 London. We don't know much about them other than they time traveled from a later date when jogging and Kleenex were normal parts of everyday life. Their words don't make a lot of sense until later in the book, but basically you could figure out that they were stuck there and had stolen some device from other people and had been helped by a woman named Grace.
The book then jumps to contemporary times, I think 2010ish, though it isn't said specifically. Gwyneth is a member of a family who has a time traveling gene. She doesn't know too much about it other than when certain member of her family is between 16 and 17, she will gain the ability to travel in time. Her 16-year-old cousin Charlotte is apparently going to be the next traveler and her family has been almost obsessed with waiting for her ability to manifest. Gwyneth, also 16, finds it all a bit weird and exciting.
Until, she starts getting the headaches which usually portend time travel and is whisked away in time. Unlike Charlotte, Gwyneth has no training and no idea what to expect.
From there she's introduced into a secret society, which was founded by the Count of St. Germain, another time traveler. He figured out what was happening and how to control it, as well as tracking down two family lines, one which passes the gene to male heirs and one to female heirs. Gwyneth is apparently the "Ruby" the last of the 12 time travelers and will have "powers of the raven".
I did figure out the truth of why her birthdate was lied about prior to the reveal in the end and have guessed about a few other storylines, but we'll see if I'm right. I did have some issues with the book but I do think it has at least started off as one of the better paranormal YA series and I look forward to reading the rest.