Read the Proclaimers book - that pretty much sums up the Watchtower side of the story.
Then get a hold of a series of articles in Watchtower from the early days called "Harvest Siftings" and you'll see both sides of the Rutherford takeover were actually published, but only one side is represented in the Proclaimers version. There are many scholars who have done thorough independent research on the early days of the Society and if you do your own research you will quickly discover that the Proclaimers book is revisionist history at its finest. There is no discussion of some of the Watchtowers greatest controversies like the Walsh trial or the Moyle trial. Also look up the Societies own actual membership statistics which are available in the predecessor of the Proclaimers book, "JW's in the Divine Purpose" and you will clearly see that around 75% of followers left the org after the controversial failed Rutherford prophesy of 1925, not just "a few disgruntled members" that the Proclaimers book claims.