Like yourself, most of my pupils started a lot younger and used kids tutor books, but I had a 13 year old start just 2 weeks ago.
It's an awkward age since the books I usually use are definitely a bit childish, so I risked using an adult book with her (Carol Barratt's, The Classic Piano Course). She seems to have taken to it like a duck to water - but she's played cello in the past and, I think, guitar, so some of the concepts are not new.
In addition, she was referred to me - her little sister's best friend is a fairly new pupil of mine - and she's been having a look at my pupil's books, which has given her a head start. We'll see how it's going in a month...
I'm sure you'll get other suggestions! Hope this helps.