In Danbury, Conn., a crowd observes a triangular craft in the air. It was part of a wave of sightings in the Hudson Valley, where more than 5000 similar events were reported between 1983 and 1986.

An Australian ranch hand races to protect his herd from a nearby object that is hovering directly over his water tower.

A biochemist watches a mysterious craft land in his yard, presenting an opportunity to scientifically examine the unexpected item.

A farmer out for a regular drive in broad daylight sees something completely out of the ordinary: a 30-foot-wide flying saucer.

On a sales trip in rural Australia, one man witnesses a strange light in a field. His car spins out of control, which is when things get even stranger.

A strange, flying object is outside an East Germany apartment complex... and then the light moves to the window.

When a police officer investigates an explosion in the desert, he sees what appears to be two small men in black. Can he trust his eyes?

It's 1975 at Loring Air Force Base, the largest strategic Air Force base in America - and a repository for nuclear weapons. Military officers at the base witness something unexplained.

Just after World War II, as the Cold War rolls on, one Swedish farmer sees what can only be described as a ghost rocket.

Dozens of people witness a strange object fall into the water and become submerged in Shag Harbour, Canada.

American soldiers stationed in England encounter unexplained lights in the forest and are given 'shoot on sight' orders.

A mysterious object stops right over John Hudson's car in the foothill of the Catskill Mountains.

A police officer spots a strange light in the sky in Minnesota. Things only get stranger after he crashes right into it... or it crashes into him.

The Hale - Bopp comet was overhead but a strange formation of lights in the sky didn't appear to be natural.

Reports of a downed aircraft bring a volunteer firefighter to a remote wooded area.

A Japan Air Lines pilot spots a mysterious object on his radar and sees bright lights outside the window of his aircraft.

On March 24, 1967, men see an unidentified object hovering over Montana’s Malmstrom Air Force Base, home to nuclear weapons, which are all disabled simultaneously.

Horses and cattle have been found dead around the world. The animals are found to be drained of blood, with their organs surgically removed. Investigators are stumped as to what could be responsible.

A fireball in the sky over Sri Lanka in 2012 is followed days later by a mysterious downpour of red rain. During the search for a rational explanation, investigators find evidence of strange living cells with no earthly comparison.

Southeast of Mexico City, hundreds goats are found dead and completely drained of blood. Is this the work of the legendary chupacabra?

Bizarre, hairless, blue-eyed and hunch-backed creatures have invaded Texas, attacking and mutilating livestock. Now there is evidence they are breeding and their population is set to explode. Scientists are mystified, the authorities are in denia ...

Hear from Director Sean Smith and go behind the filming of Fred Valentich's story - the pilot who mysteriously vanished along with his plane over Australia in 1978.

Pilot Fred Valentich's last words were "it’s above me and it’s not an aircraft." Then a mysterious metallic sounded through the radio just before the pilot and his plane vanished without a trace. Is this evidence of UFO contact?

Why would sailors mysteriously vanish from a boat, leaving behind all of their equipment with no signs of struggle?

Area 51 in Nevada is America's most secret air base. State-of-the-art aircraft have been developed here for decades, but does it also hold clues to UFOs?

A strange dog-like predator has been spotted in Texas and believed to be responsible for slaughtering livestock and draining the corpses of blood. Could it be related to the chupucabra?

Mysterious phenomena and bizarre sightings seems to follow one distinct geographic line across America: a paranormal highway.

The Flannan Isles is a desolate place, home to one of Scotland’s greatest mysteries: three lighthouse keepers who vanished without a trace. Was it a rogue wave or something more sinister?

Cusco was the capital of the ancient Inca civilization and home to some of the Incas' most sacred sites. Is this skeleton from a human sacrifice or something extraterrestrial?

In 1980, a British police officer claimed he saw a UFO. Was the sighting linked to a dead body found “as if dropped from the sky”? Was there a cover-up?

Northern Europe's Baltic Sea is one of the most dangerous seas on Earth and hides a thousand wrecks on its bottom. One massive finding under its surface isn't like the others, however.

In 1996, a startling find in Russia raised many questions. Is this a tiny, deformed baby or a creature from out of this world?