'Supergirl' Star Teases A Major Discovery

If you haven't yet seen the trailer or publicity stills for Monday's episode of Supergirl, don't! You can still experience a surprise which has inexplicably been spoiled over and over again in promotional material for the episode.

Okay, fine. If you are still here, and haven't yet been spoiled, here's a hint: series star Melissa Benoist sat down for a recent interview and, rather than immediately jumping to the punchline like the trailers did, she teased what is coming.

"There is possibly a way to defeat Reign, which obviously Kara and Mon-El want to check out," Benoist told EW. "So I think they find something in space that, to say the least, neither of them or anyone watching the show will expect them to find."

What they find -- in space -- has already been revealed in trailers, and while it may seem impossible to believe, the report assures readers that there is no misdirection at play.

At the end of last week's episode, the DEO found an item in space that they believed would be help in defeating the last of the Worldkillers. Supergirl and Mon-El took off into space to find it at the end of the episode.

Beyond this point, we will be discussing the spoiler, which feels like fair game since we have not only warned you but, again, The CW has repeatedly spoiled their own reveal.

Promotional materials for next week's episode, titled "Dark Side of the Moon," have revealed that Supergirl will learn something pretty significant about Krypton's past -- namely that not everyone died.

Her mother Alura appears in the trailer and publicity stills for the episode.

That means the object Supergirl and Mon-El are headed toward is likely Argo City, a major city-state that shared a continent with Kryptonopolis and Kandor in the comics. Argo is generally depicted as having survived Krypton's destruction atop a large chunk of the planet, sent hurtling intact through space.

Krypton, SYFY's Superman prequel, takes place in Kandor.

In the comics, various stories have taken place on Argo City. Protected by a dome reminiscent of Brainiac's bottling technology, Argo manages to sustain life -- at least for a time. In the 1984 Supergirl movie, Kara is there as an adult before she has to go to Earth in order to retrieve a lost power source, the absence of which would doom Argo.

The title "Dark Side of the Moon," besides being the name of a Pink Floyd Album, is likely a nod to the fact that in the "New Krypton" storyline in the comics, Superman helped the survivors of Kandor's bottling to settle on Earth's moon.

Supergirl will return for its fourth season in the fall. The series will air on Sunday nights at 8 p.m. ET/PT on The CW.