Christof investigates UFO sightings in the United Kingdom and Canada; he soon uncovers a much bigger story about governmental secrets.

Christof investigates the robbery of the Isabella Stewart Gardner Museum, which is the largest art heist in history; in pursuit of the stolen masterpieces, he follows leads from members of organized crime that take him to Florida and France.

Christof joins the decades-long hunt for the buried millions of notorious gangster Dutch Schultz; armed with rare documents and cutting-edge tech, Christof follows the fugitive mob boss' trail from Saratoga Springs, N.Y., to Miami.

Christof jumps from a plane and digs up rare FBI files as he follows new leads that take him from the Pacific Northwest to Las Vegas and Utah in his quest to find the real identity of hijacker D.B. Cooper.

Christof uncovers new clues about the true fate of Wild West outlaws Butch Cassidy and the Sundance Kid; he travels to the highlands of Bolivia and the mountains of Utah to dig up evidence that may finally solve this 100-year-old mystery.

Christof Putzel hunts down inside information regarding three prisoners who escaped from Alcatraz in 1962; while authorities are certain that the men drowned in the waters surrounding Alcatraz Island, FBI files say otherwise.

Christof investigates the Lindbergh kidnapping, a story that made his grandfather's journalism career; using his grandfather's notes and recently declassified FBI files, Christof tracks down surprising new leads to Germany and even the Nazi Party.

A century ago, New Orleans is terrorized by an ax murderer; now, Christof discovers new leads that could point to some of the earliest mafia hits; his research into the Axeman of New Orleans takes him from the Big Easy to Sicily and Los Angeles.

Christof digs into the Black Dahlia murder, one of the most infamous unsolved murder cases in Los Angeles history; he uncovers an investigation derailed by corruption and finds a confession pointing him to a new suspect in the Philippines.

Unfold the truth with Brad Cartner as he steps behind the scenes of some of the most amazing UFO stories around. The team investigates why there are so many sightings in and around nuclear facilities, the differences with shapes of UFOs, a mysterious air raid in Los Angeles, Roswell and the fabled crash site. Also delve deeper into if UFOs are a threat to our aviation and how pilots react when they encounter UFOs in the air.

Conspiracy theories, mysteries, secrets and the forbidden are probed with a fresh set of eyes as "America Declassified" delves into the hidden side of the United States. Investigators including former CIA officer Mike Baker, geoscientist and radiological engineering consultant Ben McGee, and investigative reporter Michele McPhee go on location to examine stories and events using new evidence, unprecedented access and never-before-heard-from witnesses. The hourlong episodes incorporate scientific methods, forensics and state-of-the-art surveillance technology to gain new insight into John F. Kennedy's assassination, the D.B. Cooper hijacking case, most-wanted mobster Whitey Bulger's life on the lam, and a rumored doomsday bunker under a major U.S. airport, among other stories. Locals and eyewitnesses also share their accounts of strange sightings, weird goings-on and unexplained phenomena.

Former House Intelligence Committee Chairman Mike Rogers hosts this CNN original series, an eight-part look at complex true stories of America's covert operations. The newly declassified missions are recounted firsthand by agents from all 16 U.S. intelligence bureaus, providing viewers with unprecedented access to a secret world of espionage. The missions span time periods from Cold War-era Moscow to modern-day Iran, from the streets of 1980s Cuba to Beijing of today. Among the stories covered are the military's hunts for Iraq dictator Saddam Hussein and al-Qaida leader Abu Musab al-Zarqawi.

As host of popular series including "Expedition Unknown" and "Destination Truth," adventurer and avid explorer Josh Gates has visited more than 100 countries. Some journeys, of course, have stood out more than others, and on "Legendary Locations," Gates showcases magical places around the world through his unique point of view. Each location has an unforgettable backstory, a secret origin or a forgotten lore, like an ancient city carved into Jordan's sandstone cliffs, a favorite summer getaway of notorious drug lord Pablo Escobar, and an Irish landscape now known as Luke Skywalker's lair. With every spin of the globe, Josh investigates ancient legends and surprising folklore that travelers and locals alike love to experience.

As the host of numerous Travel Channel docuseries aimed at exposing truths lying beneath the surface, Don Wildman has ventured deep into the vaults of America's most revered institutions and unearthed wondrous treasures from the past. In "Beyond the Unknown," Wildman's adventures continue, as he seeks to answer history's biggest questions and explores the most astonishing and explainable events in recorded time. Each story features interviews, archival footage and stylized reenactments.

Recently declassified U.S. documents reveal America's aggressive and controversial methods to stay ahead of the Soviets during the Atomic Age.

Travel Channel's fascination with mysteries grows with this series, adding it to a catalog that also features "Mysteries at the Castle," "Mysteries at the Museum" and "Monumental Mysteries." America's vast network of national parks -- dense expanses of virtually unexplored wilderness -- offers breeding grounds for the unsolved and unexplained. Each hourlong episode presents several perplexing stories detailing unusual events at sites including Montana's Glacier National Park, Pennsylvania's Gettysburg National Military Park, California's Shasta National Forest, and Puerto Rico's El Yunque National Forest.