‘The Flash’ Sneak Peak: Episode 15 is the ‘Best Episode’ Yet

Fans of the "The Flash" will be shocked by the end of tonight.

According to E! News, who got a sneak preview of episode 15, "Out of Time," the superhero CW TV series will blow everyone's mind. E! News is reporting that a massive cliffhanger will leave you with your mouth wide open, thinking "How was that not the season finale?!"

Actor Tom Cavanagh, who plays the mysterious Dr. Harrison Wells who is also known as Reverse Flash, described the episode as, "Hashtag gamechanger!"

The executive producer Andrew Kreisberg added, "With no disrespect to any of the other directors or episodes that we have produced, I think this is the best episode we've ever done. Everything that The Flash can do-and I don't mean Barry Allen [Grant Gustin] as the hero, but as a TV show-this episode delivers in spades. It's got amazing visual effects that you don't see on television, it's full of heart, it's full of romance, genuine scares, and it's the best version of this show. Between this and Arrow, there's only a handful of episodes we say this about and I definitely feel like this is it."

In tonight's episode, fans can expect several plotlines.

1. Barry, Iris and Eddie Love Triangle Gets Complicated

The relationship between Barry and Iris, played by Candice Patton, will get complicated. Iris and her cop-boyfriend Eddie (Rick Cosnett), who is also her dad's partner, will go on an awkward double date with Barry and his girlfriend, Linda.

"It's fun, because Barry's oblivious to anything being wrong with the date," Gustin told Variety at PaleyFest. "He had a great time. There aren't any immediate repercussions, but it's a first step in a series of things that create some issues for Barry's current relationship."

Watch a preview of the date here:

2. A metahuman seeks revenge

Fans will see Mark Mardons (Liam McIntyre) on an angry journey to avenge the death of his brother, Clyde Mardon (Chad Rook), who was killed by Joe (Jessie L. Martin). Mark will appear in at least two more episodes.

"It's pretty simple: revenge for his brother," Kreisberg says of Mark's motivations. "Liam is so great as Spartacus but now he's so great as the villain in this. People are going to be surprised at how good he is at playing the dark, evil character. We wanted a Weather Wizard who was more in control of his abilities and less beset by them. Mark's obviously had more time to control it."

3. Someone will die

A character will die in tonight's episode. Although we do not know whether or not the person is a main character, E! News reports that fans will be "absolutely gutted."

4. Wells' secrets are close to surfacing

Throughout the season, Wells' team, Caitlin Snow (Danielle Panabaker) and Cisco (Carlos Valdes) have trusted him. In tonight's episode, however, they will start to question his motives.

"The Flash" airs at 8 p.m. on Tuesdays on CW.

Watch the PaleyFest Trailer here: