The series revolves around the real-life Project Blue Book, a secret series of investigations into supposed UFO encounters and unexplained phenomena undertaken by the United States Air Force with skeptical astrophysics professor — and eventual ufologist — Dr. J. Allen Hynek in the 1950s and 1960s. With his partner, Air Force veteran Captain Michael Quinn, they investigate sightings across the U.S., and Dr. Hynek discovers that not everything can be explained by science.