This is an odd book that inhabits the intersection between detective noir and comic fantasy. It has its moments and contains quite a few imaginative ideas but in the end it's a disappointment.
The hero is Charles Unwin, a clerk for the city detective agency. When the detective he works for - Travis Sivart - disappears, Unwin finds himself unexpectedly promoted to detective. He's handed a book, The Manual of Detection, and left to get to work.
Unwin sets out to find Sivart but only because finding him will allow him to go back to being a clerk. His investigation turns up a complex mystery involving a casino whose patrons gamble alarm clocks, a tumbled-down circus whose mysterious owner may be planning to take over the city and a pair of former conjoined twins who act as heavies.
There are some nice touches. The detective agency, which seems to be the only source of law and order in Berry's world, is housed in a tower that dominates the skyline of a city in which it's always raining and usually night time. Unwin is a likeably self-effacing, barely competent hero who chases down leads on his bicycle.
Berry draws on a range of influences. There are touches of Terry Gilliam's film Brazil, Douglas Adams's Dirk Gently novels, the detective novels of Chandler and Hammett and even Scooby Doo. Unfortunately, I didn't feel that the various elements cohered in a convincing way. Though Berry is a decent writer, the book fails to rise above the level of its influences.