Well, I am not sure how I missed out on books 1-20, but yes, this is the 21st in the Doc Ford series. It is definitely a stand alone book, and I never felt I was missing something in the story by not reading the previous books.
I enjoyed the main characters in this story. Doc and his sort of ex Hannah are an interesting mix, and I enjoyed the differences in their personalities. The story progresses smoothly as Doc is approached to help a member of the Crow Nation recover a stolen relic. The job leads him on an adventure into stolen artifacts, the black market, environmental concerns of phosphate plants, and relic diving. The location descriptions gave a real sense of being in the heart of Florida.
I thought the plot got a little confusing with so many minor characters and it slowed the story down a bit, but it was still a good book and I will definitely look at some of the previous books in this series.