https://www.goodreads.com/book/show/10255.Dr_Mary_s_Monkey
The 1964 murder of a nationally known cancer researcher sets the stage for this gripping exposé of medical professionals enmeshed in covert government operations over the course of three decades. Following a trail of police records, FBI files, cancer statistics, and medical journals, this revealing book presents evidence of a web of medical secret-keeping that began with the handling of evidence in the JFK assassination and continued apace, sweeping doctors into coverups of cancer outbreaks, contaminated polio vaccine, the arrival of the AIDS virus, and biological weapon research using infected monkeys.
I think I know what you mean about the narrow focus. I see it often, where a subject is being covered in detail but the subject touches on other areas that are huge on their own. It almost seems absurd to not dive deeper into all aspects, but geez, the book would be pretty thick by the end. I feel like nearly every "conspiracy" topic ties right back into one giant taproot.
What it covered, Mary's Monkey covered well. And yes, the tangents equally explored would fill volumes.
The Dr. Tent video that I linked in the comments does the opposite. It goes into the history of vaccines and their role in causing illness, and teasingly relates it all to Dr. Sherman's activities.