The two books in questions are The Sentence is Death and The Word is Murder. I believe there's a third book due out sometime.
   So Daniel Hawthorne is Horowitz's detective. He's not especially pleasant but he does go around solving mysteries. The twist is that Hawthorne's 'Watson' is Horowitz himself, who follows Hawthorne around, recording what happens, ready to write a book about it all.
   This works reasonably well.
   What doesn't work quite as well is that, apparently, this is Horowitz's efforts to write 'adult' novels (he is, of course, famous for writing for young adults). It doesn't quite come off, in my opinion: the contents might be more adult, but the style of writing is still young adult.
   That said, I enjoyed the books and enjoyed trying to figure out what was going on. Horowitz can cook up a mean plot. I certainly wouldn't dissuade anyone from reading these two books... and no doubt I will find myself the third one sometime in the future.