Josh Gates investigates the most mysterious airline disaster in American history, searching for why Northwest Flight 2501 vanished taking the lives of all 58 people on-board. Later, Josh and his team examine sightings of the Mothman across the Midwest.

Josh Gates continues his epic investigation as he ranges across Africa to study wild chimpanzees and scales sheer cliffs on his quest for the missing links of human evolution. In Mexico City, the Expedition X investigation puts the team's safety at risk.