"Game of Thrones" fans who tuned in Sunday night to watch the epic "Battle of the Bastards" were treated to -- and creeped out by! -- the first trailer for HBO's "Westworld."

Based on Michael Crichton's 1973 film of the same name, the sci-fi thriller is "a dark odyssey about the dawn of artificial consciousness and the evolution of sin," set in a futuristic theme park called Westworld. "I think there may something wrong with this world," we hear in voiceover, "something hiding underneath."

Created by Jonathan Nolan and Lisa Joy, and executive produced by J.J. Abrams, the series features an all-star cast that includes Anthony Hopkins, Ed Harris, Evan Rachel Wood, James Marsden, Thandie Newton, Jeffrey Wright, Tessa Thompson, Sidse Babett Knudsen, Jimmi Simpson, Rodrigo Santoro, Shannon Woodward, Ingrid Bolsø Berdal, Ben Barnes, Simon Quarterman, Angela Sarafyan, Luke Hemsworth and Clifton Collins Jr.

"Westworld" premieres in October on HBO.