The Monsters Inside by Stephen Cole is the second novel in the Doctor Who New Series Adventures and features the Ninth Doctor and Rose Tyler, as portrayed on TV by Christopher Eccleston and Billie Piper. It also features a second encounter with the Slitheen, as well as another family from Raxicoricofallapatorius, the Blathereen. This book was also the first story featuring Rose, televised or otherwise, to not take place on Earth. The first line of the book is "Wherever it was, it wasn't Earth." and the acknowledgements thank Russell T. Davies for allowing the author to take Rose to her first alien planet.
I was very impressed with this book. I think the author of this book did a much better job of capturing the characters of the Ninth Doctor and Rose Tyler than the previous novel, The Clockwise Man. It definitely had me hooked from very early on and was very much along the lines of what I would have expected to see on-screen. Interestingly enough, the Blathereen are mentioned again on The Sarah Jane Adventures, and the planetary system this story takes place on, Justicia, is mentioned in the episode Boom Town which makes this the first novel to be referenced on-screen.
Next up, Rose and the Ninth Doctor return to Earth and team up with Mickey Smith in Winner Takes All, the final novel in the first batch of New Series Adventures to be released.