This interview contains spoilers for the Project Blue Book Season 1 finale, “The Washington Merry-Go-Round.”
At the end of the Season 1 finale of Project Blue Book, J. Allen Hynek is a man on his own. Following the Washington Flap — a series of famously well-documented real-life UFO sightings in 1952 fictionalized on the show — he is warned by mysterious allies they can no longer protect him. But as Hynek looks to the stars from his observatory, Aidan Gillen, who portrays the UFO researcher, is looking ahead to the second season of the History show.
Gillen didn’t know about the Season 2 renewal when the finale ended on that cliffhanger, which also showed Hynek – in a move worthy of the actor’s character Littlefinger from Game of Thrones — apparently doublecrossing his partner Quinn (Michael Malarkey), only to reveal he was actually pulling the wool over the government’s collective eyes.
Source: IGN.com Project Blue Book's Season Finale Ends on a Major Cliffhanger