For me it would be the topic of the true nature of the planet we live on or the concept of Hollow Earth. I found out about it while researching the ancient pyramids and the Piri Reis map both very interesting topics themselves but the concept that our planet is hollow with an inner Sun rings true to me and explains so many myths, legends and disinformation that it was very easy for me to research.
What I find most perplexing is if it is just a fantasy, then why ban books on the subject or censor information about it, why the secret.
However upon reading extensively on the subject I now understand why, as it explains UFOs, Extraterrestrials, the Bible (Genesis), Ancient Man, the Aurora Borelias, the Polar Shift, and so many legends and myths of ancient lore that there is no doubt in my mind that it is true.
It explains the ancient legends of Atlantis and Lemur, how the Tibetan monks have gained such valuable spiritual knowledge, why and how the Freemasons and Illuminati gain so much power and how The Powers That Be have such much power over the surface of the planet.
Why there is a no fly zone over the poles, why the Nazi's were so interested in Antarctica and the list goes on and on.
Hollow Earth explains the how and why humanity is what it is and where we are going as a species.