I like The Brothers Bulger more than Black Mass to be honest. But if you want the most detailed account of Whitey's life (including the LSD experiments which he did take part in), the best book IMO is "Whitey", also by Gerard O'Neill and Dick Lehr. It came out in the past year or so and has a lot of previously unpublished info including a lot about Whitey's earlier years all the way to his years as a fugitive. I highly recommend that as the best book about Whitey, with Brothers Bulger second.