The Angel EffectThis documentary tries to break the barrier between science and the supernatural. It is based on Geiger's book The Third Man Factor: Surviving the Impossible, which profiles people in high-risk occupations who have survived near-death experiences with assistance from an unseen presence.

A 9/11 survivor, an astronaut and a sea diver - each felt a mysterious presence that guided them to safety in their time of greatest peril.

"This phenomenon is tremendously underreported," Geiger told TV critics. "When I started looking into it, climbers, solo sailors, shipwreck survivors, polar explorers - none wanted to talk about it because they're very tough men and women, and to concede there may be something else at play might be perceived as a sign of psychological weakness."

Geiger appeared at the National Geographic session alongside NASA astronaut Jerry Linenger, who spent several months aboard the Russian space station Mir on what was later described as the most dangerous mission in space travel history.

Linenger claims he felt the presence of his deceased father during the disastrous mission's lowest ebb. "I heard him talking to me, saying, 'Jerry, I'm proud of you. You always wanted to be an astronaut. You're going to make it through this.' And it was a positive thing that got me through the situation," said Linenger.

Watch the full documentary now