Marvel 'Thor: Ragnarok' Spoilers: Australian TV Host Reveals Major Plot Twist in Chris Hemsworth Interview—This Is What It Means

That sound you hear is Marvel's S.H.I.E.L.D. agents parachuting into Australia to contain a new threat.

Thor: Ragnarok stars Chris Hemsworth and Mark Ruffalo stopped by The Project, an Australian talk show Monday, to talk up the new blockbuster. But in the process of the interview, one of the show's hosts inadvertently dropped a major, major spoiler for the movie.

Of course, Ragnarok—Hemsworth's third solo outing as the Norse god—is not due in theaters until November 3 in the U.S., and a week earlier in Europe. So, spoiler-phobes beware, if you don't want the plot ruined, look away now.

OK, since we're now among friends, here be spoilers.

The Project host Tommy Little gave away a huge secret about the Thor: Ragnarok plot while talking to Hemsworth and Ruffalo about the flick.

Little revealed that Cate Blanchett's villain, Hela is, in fact, Thor's sister. This has not been revealed in any marketing material or trailers, and Marvel clearly wants it to be a surprise for moviegoers when they see the film.

Little didn't just drop this bombshell once, but mentioned the plot twist once again. Hemsworth, 34, looked a little annoyed, but played it off.

"The gorgeous Cate Blanchett plays your sister, Chris," Little said.

He followed up, "Your sister, she's trying to kill you…" and it was at this point Hemsworth intervened: "You can't give that away."

"This is not live is it?" Hemsworth joked. "We can rewind?"

Sadly, Chris, it was totally live.

Who is Hela?

The Marvel Cinematic Universe backstory for Hela, as the brother of Thor and daughter of Norse god Odin, diverges from her origins in Marvel comic book lore.

In the Marvel comics, Hela is the daughter of Loki, but not the Loki we know today—as played by Tom Hiddleston—but a previous incarnation of the god of mischief. Her mother is a giant sorceress named Angrboda.

As a god in her own right, Hela possesses super-strength and other qualities that make her more than a competent match for Thor.

Hela was appointed the goddess of death by Odin, however, when her overzealous desire for power ultimately led to her being ostracized and coming into conflict with Odin and Thor.

In one comic book arc, Hela worked together with the current incarnation of Loki to enact Ragnarok, the cyclical apocalypse that befalls the mythological Asgard and leads to the rebirth of the Asgardian race.

Marvel 'Thor: Ragnarok' Spoilers: Australian TV Host Reveals Major Plot Twist in Chris Hemsworth Interview—This Is What It Means | Culture