" Okay. Now my skin is really prickling. I've read all the Harry Potter books, all five of them. I don't remember any half-blood prince." What's this?" Trying to sound casual, I point at the ad, " What's Harry Potter and the Half-Blood Prince?" " That's the latest book," Garth the other trainee, says. " It came out ages ago." I can't help gasping. " There's a sixth Harry Potter?" " There's a seventh out soon!" Diana steps forward eagerly. " And guess what happens at the end of book six-" " Shh!" exclaims Nicole, the other nurse. " Don't tell her! "