The show follows numerous investigations (referred to as "cases" in the beginning of each episode) led by
William J. Birnes and his team of experts: researcher and scuba diver Pat Uskert, mechanical engineer and
MIT researcher Ted Acworth, and investigative biologist Jeff Tomlinson. In the second season, Tomlinson departed. In the third season, Acworth was replaced by mechanical engineer Kevin Cook. In each episode, the team investigates reports of
unidentified aerial phenomena, including interviewing witnesses of
close encounters with UFOs, USOs (unidentified submerged objects), and supposed
extraterrestrial life. They also analyze any evidence collected such as photographs, video, or recovered physical material. They also conduct research with other investigators and scientists in the field in an attempt to find conclusive evidence that a report is real or a hoax. The show includes investigations of long-standing UFO cases, such as the
Roswell, New Mexico UFO crash incident and other famous sightings throughout history. The opening theme song "The Only One" was performed by the band
Operator. In later seasons the song was removed and the opening theme was changed. == Series overview ==