`Expedition Unknown' has taken Josh Gates to the ends of the Earth and back to investigate iconic unsolved events and other puzzling stories. Now, he's searching for evidence that life exists on other planets. `Hunt for Extraterrestrials' takes Josh to four continents to uncover the truth behind extraterrestrial legends and mysteries. Along the way, he visits NASA's mission control center in Houston, where `international travel' takes on a whole new meaning. Gates also attends the UFO Festival in Roswell, N.M., participating in the out-of-this-world festivities that celebrate America's most famous UFO case.