Watch sinister shapes hover over Chicago and Ruwa, Zimbabwe. Meet an Australian fighting for his life after taking a blast from a mysterious object, then hang back as a UFO appears to taunt a US military fighter jet over the Bermuda Triangle.

Was Einstein a witness to a crashed disc? Was the ancient site of Gobekli Tepe built by aliens? Was Erich von Däniken correct about Ancient Astronauts? And was a 1950 German UFO case covered up? These mysteries remain unexplained.

Digging into a UFO crash caught on camera in Brazil; a close encounter of the Beatles kind; finding out if aliens shut down a nuclear missile launch site in Montana; looking at the shapes of UFOs and considering a link between ghosts and aliens.

Accounts of an amphibious UFO in Indonesia; a mass abduction in Australia; a slew of deaths in Wales after a strange sighting; searching for an alien library with an astronaut and meeting a scientist hunting for an interdimensional portal.

Taking a look at strange crafts flying over power plants, airports and the Royal Palace in Sweden, a veteran with supposed UFO-related health issues and footage shown at a US congressional hearing.

Investigating reports of UFOs massed over the South China Sea, ancient carvings of alienlike humanoids, and Albert Einstein's secret 1947 visit to Roswell, New Mexico.