The 11th season premiere of "History Detectives," which has been reformatted to focus on one iconic mystery per episode, opens with a look at the April 27, 1865, explosion of the Mississippi steamboat SS Sultana, which was packed with Union soldiers. One of the worst maritime disasters in U.S. history, the official death toll was 1547. The team reviews the original investigative report; and examines theories about the cause, including that it was an act of sabotage by a Confederate agent.

An investigation into the disappearance of Glenn Miller during World War II. On December 15, 1944, the Army Air Force plane carrying him from England to France vanished while flying across the English Channel. The report makes use of a plane spotter's notebook that was discovered in 2012 to pinpoint the path of Miller's plane; and digs into several theories, including one that friendly fire downed the plane and another that he was on a secret mission to end the war.

The unsolved case of the Servant Girl Murders in 1884-85 Austin, Texas, is investigated. Over the course of a year, six African-American servants and two white women were brutally murdered. The modus operandi was similar in each instance: the assailant attacked the victim with an ax while she slept in bed; and then he dragged her outside, where he raped and mutilated her.

An investigation into the disappearance of Jimmy Hoffa, the former Teamsters president, who was last seen outside the Machus Red Fox Restaurant in Bloomfield Township, Mich., on July 30, 1975.