The investigators monitor the activity of the AUTEC (Atlantic Undersea Test and Evaluation Center), which is used by the U.S. Navy for underwater research, but the increasing reports of UFO and USO activity surrounding the facility have lead to rumors the base is testing alien technology.

The team finds new vantage points to spy on the recent activity at Area 51, which in the past decade has acquired more public lands to increase perimeter security, and built new towers, buildings and runways for the continued development of top secret aircraft.

The team looks into the claims of undercover investigators and former military personnel that an alien base exists somewhere below the New Mexico desert where human-alien hybrid experiments are being performed and how the beings there actually had a deadly conflict with human infiltrators.

For years, the team has been tracking an elusive prey only seen at night--ships, shaped like triangles, impossibly huge, and videotaped over cities around the world. But are they ours, or theirs? The team investigates numerous UFO sightings that have recently been reported in Sonora, California, a charming old West town nestled in the Sierra Nevada Mountain Range nicknamed Triangle Alley. What makes these sightings so compelling are rare daytime footage of triangles in flight. This footage will be digitally analyzed to determine if these are indeed UFOs and not military jets. The team will also visit Texas to speak to military experts and witnesses to compelling triangle sightings. It's speculated that these triangle craft have been visiting us for centuries

The team ventures to Germany and Poland to investigate rumors that the Third Reich had reverse engineered alien technology and may have produced a functional spacecraft, and how some of this technology was captured by the United States and helped jump start the U.S. space program.

A strange object was seen flying toward Bentwaters RAF base in England, a base holding nuclear materials. The team investigates and Nick Pope, former British Prime Minister of Defense, speaks about the incident.

Police officials in Ohio, Michigan and Illinois talk about the cases of UFO they have examined in their areas.

n the early 1950's, James McDonald, a senior physicist at the University of Arizona, changed the entire course of UFO research. For nearly 20 years he examined UFO reports in great detail – interviewing over 500 witnesses, uncovering important government documents, and testifying before Congress in 1968. He challenged skeptics, performed scientific analysis, and led the charge for UFOs to be properly studied. After his tragic death in 1971, his investigations and files were sent to the University archives, where they lay dormant...until now. The team brings these lost UFO files back into the public eye for the first time on television, and looks at evidence long thought lost to history.

The investigators analyze various UFO cases from around the world through the Freedom of Information Act, separating fact from fiction to determine what are obvious hoaxes and what could be legitimate evidence of UFO phenomena.

Continuing on the trail of the MIBs, the hunters follow the agent's supposed connections to a remote, military testing facility, the Dugway Proving Ground near Dugway, Utah. Dubbed by UFO watchers as "Area 52" and "the New Area 51" there have been numerous reports and video evidence of UFO activity surrounding the base for the past 10 years.

The team reviews footage from NASA showing unidentified objects in space. Apollo astronaut Edgar Mitchell and former NASA contractor Donna Hare are interviewed.

The team tries to gather insight on the military's "First Response" protocols, the alleged recovery and cover-up procedures that are followed in case of a UFO incident. The investigation takes them to a claim of a military pursuit of multiple UFOs near Long Beach, California and a return visit to the supposed UFO crash in Needles, California in 2008.

A triangular-shaped aircraft seen over Tinley Park, Illinois is investigated. Similar reportings were made around the same time all around the world.

A retrospective which examines the July 1947 in the New Mexico Desert of Roswell, where an alien ship purportedly crashed. Included are new theories, among them is a second crash may have occurred.

The team probes the skies over England following an airline pilot's official report of a pair of UFOs he believed to be at least a mile in length, and a review of other sightings of gigantic unidentified craft seen over the United States.

The hunters investigate the growing number of encounters between commercial aircraft and UFOs, highlighting a November 2006 incident at O'Hare International Airport in Chicago and a 2004 sighting in Osaka, Japan.

The hunters delve into cases involving witness interrogation by mysterious agents known as the "Men in Black" (MIBs), who sometimes appear suddenly after a UFO event, exhibit unusual behavior, know facts that have not been divulged by witnesses, and threaten the lives of those involved with severe consequences unless they remain silent about their encounter.

The team interviews Terrell Copeland, a retired member of the US Marine Corps, and Michael Lee Hill, a resident of Lake Erie, about seeing unidentified objects. Their stories are found to be eerily similar.

The team is hot on the trail of a case that just happened, one that had the whole country talking just weeks ago. In December 2007, people begin seeing UFOs in the skies ninety miles from Dallas, Texas. Within a month, the reports had increased ten-fold. The UFO Hunters travel to Stephenville, Texas to investigate the strange lights in the sky. They meet witnesses never interviewed for TV, analyze strange footage shot by people all over Texas, and come to an incredible conclusion.

The hunters try to find what the military covered up in a recent May 2008 crash of an unknown object in Needles, California, and looks at other famous crash incidents like the Kecksburg, Pennsylvania case where the military supposedly undertook a massive clean up effort and intimidated local witnesses.

The team investigates the phenomena of cattle mutilations, investigating a recent slaughter and following patterns of other cases, as well as sightings of black helicopters which have led some to believe the military may be involved in the killings as part of a secret experiment.

Six unidentified objects were seen near Maury Island, Washington; two Air Force officers later came to the site, investigated, and collected evidence. Their plane crashed near Kelso, Washington. The crew analyzes the crash site and looks at evidence.

The team checks out the reports of Unidentified Submerged Objects (USOs), one of which reportedly caused the crash of a single-engine light aircraft, off the coast of Santa Catalina Island, California.

Claims of objects being implanted in human beings by alien abductions are investigated by the team, along with the help of several accredited doctors and scientists.

The team travels around the country to hear first-hand accounts from police officers of unexplained sightings.