For as long as there have been sightings of strange objects in the sky, there have been reports from those who say they've encountered entities associated with the phenomena. Despite the stigma attached to speaking out, people share stories of their extraordinary interactions.

A revealing look at what happens when the phenomenon gets deeply personal. Beyond sightings in the sky, people relive encounters they describe as abductions. Renowned Harvard psychiatrist John Mack, comes under attack for taking them seriously.

An explosive congressional hearing reignites a decades-long fight for government transparency on UFOs. A whistleblower provides explosive testimony. Fighter pilots and military personnel describe strange sightings, and the U.S. government is forced to consider a new approach to how they analyze and make public UFO sightings.

A former Navy pilot, who helped blow the whistle on the government's secrecy around UFOs, becomes an advocate for commercial pilots who have nowhere to report the sightings their trained eyes cannot explain. Activists push for legislation to address the toll, the issue takes on pilots.

Scientists across academia take matters into their own hands, employing a variety of cutting-edge tools to study UFO phenomena. Using AI, precise radar systems, advances in physics and analyses of historical images, they hope to collect data that reveals the source of these mysterious sightings.

Area 51, a military outpost in the desert, shrouded in secrecy for decades, has long been the focus of many Unidentified Aerial Phenomena or "UAP" rumors. A pop culture phenomenon, Area 51 prompted one Facebook group to suggest storming the facility in search for answers. Civilian UAP groups continue making progress in providing those answers. For the first time since 1969, Congress questions high level officials in the Pentagon on UAPs.

For more than five decades the US government has refused to discuss UFOs, but now, Navy pilots tell of seeing mysterious objects tracking their fighter jets – vehicles unlike anything they’ve ever seen before; top-secret Naval videos are leaked that captivate the world. Government officials, led by former U.S. Senator Harry Reid, demand an investigation. At long last, it looks like the truth about UFOs may finally be revealed.

In 2008 in Stephenville, Texas a local pilot sees lights in the sky over his ranch coming from something huge. He is not alone: hundreds of people saw the craft, and a local reporter makes it her life's work to tell their stories. From this classic encounter we head back several decades to the beginning of the UFO phenomenon in America and the launch of Project Blue Book to study the country's growing "UFO problem".

Project Blue Book and the investigation into UFOs closes. There is no evidence that mysterious objects represent any threat to U.S. national security. But harrowing incidents of UFO sightings continue and the unexplained malfunction of U.S. nuclear missiles after an incursion leave the U.S. defenseless. Three former Air Force officers, who served at nuclear weapons bases in the late 1960s, break two decades of silence to tell their story.

From a 1986 sighting over Alaska by Japanese Airline pilots, to a 1997 UAP sighting over Phoenix Arizona and a flying disc over the Chicago O'Hare airport in 2008, hundreds of witnesses come forward without any official feedback from the US government. Years later, many of the pilots and government officials, who witnessed these sightings, come together for the first time to share their story in a 2007 press conference.

No longer waiting for the government to reveal everything they know about UFOs, citizen scientists and privately funded organizations are making advances in data collection. In the air and under the seas, exploration continues to push for answers to the ultimate question: Are we alone?