Bargain books

Got two books for 10p at our local library sale. One looks very promising - Time of Terror by Seth Hunter, lovely AOS stuff. Other one made me a bit cross. Historical mystery, one of a series, set in Victorian times - the reader knows from the first murder that there was a female accomplice but she didn't appear in the book until 30 pages from the end and her identity couldn't have been deduced. Not playing fair!