In a remote area of Alaska, researcher Philip responded to a mysterious anonymous letter and set out on a quest to learn the truth about Flight 66, a jet said to have disappeared en way to Japan.

Via hints and local lore, he was guided to a hilly region where the plane’s wreckage might be seen.

The true surprise, though, was what was inside: gold-filled containers, a single bullet that had been squashed, and an oddly vacant cockpit. The mysterious tip-off source behind this revelation remained unidentified even while authorities took action.

While there are still many unanswered questions, Philip’s amazing discovery was made famous in a best-selling book. Although being uncovered, Flight 66 still holds a lot of mysteries, particularly in regards to the mysterious informant.