It depends on your definition of good!

If you want a good read but may not be all factual, then you go can to "Death Makes A Holiday: A cultural history of Halloween." Its written by David Skal. Although it sounds scholarly, it is published by popular press and he is not a historian but rather a "cultural critic."

If you want good as in a scholarly and peer reviewed source of information, then "Halloween: An American Holiday, An American History" written by Lesley Bannatyne. It is published by Oxford Press, and is quite an interesting read!

Or you could go with an early history written by Ruth Edna Kelly in 1917 called "The Book of Hallowe'en." I haven't personally read it so I can't comment to its readability or credibility. But it's there if you would like to read it!

Hope this helps!