The Returns covers from the end of the first film to to the start of the second (1955-58) and then after the sequal bulk of the second film (59-62) It also has a brief section on Michaels childhood and his time in the war. I'm hoping that in the next book, it shows more of Mike's relationship with his brothers.

I dont know what years the final book covers, but at a guess it'll be 62-79 to take us to the start of part III.