This is the most definitive biography on Spencer Tracy we will ever have. No one else will have as much access to the private library of Tracy's photos, scrapbooks, datebooks, etc. as well as access to the people who knew, loved and worked with Spencer Tracy as James Curtis did. It's a honking book clocking in at 878 pages of content and if you include the front and back matter it's over 1,000. I felt like I had just run a marathon when I finished it. Its worth the effort and time. The book is chock full of information. Take it one chapter at a time otherwise you'll feel overwhelmed. Everything is covered here but Curtis never feels the need to go into any salacious detail.
See my full review here: http://outofthepastcfb.blogspot.com/2011/12/get-your-read-on-spencer-tracy-by-james.html