One of the early Torchwood books – set just before Cyberwoman, I think. Andy Lane has written some good Who novels and this too is excellent; good depictions of all the team (not much Ianto, but lots of Owen), and of how alien tech threatens to infilltrate Rhys and Gwen’s relationship. I was also impressed by the first season Torchwood novel Border Princes, and on the basis of that and this will now be looking out for more of them.