Arrow's Gasp-Worthy, Finale-Caliber 'Betrayal' Will Leave You Screaming at the TV -- But Why?

Arrow Spoilers -- Betrayal Episode 13Stephen Amell and his castmates have a lot to say — and yet little to reveal — about Arrows 13th episode, titled “Betrayal” and airing tonight at 8/7c on The CW.

RELATED | Arrow Targets ER Alum to Play Laurel’s Mother

On the surface, the episode guest-stars David Anders (Alias, Once Upon a Time) as Cyrus Vanch, a nefarious criminal resigned to reclaim his position atop the underworld after release from prison. That agenda thusly lands Starling City’s hooded vigilante in his crosshairs.

“He is a different kind of villain,” Amell shared during our visit to the set, as “Betrayal” was being filmed. “If The Count was very diabolical and scheme-y, this guy is sort of reckless and incredibly confident. And I don’t go after him; he comes after me, which is a change for us.”

To that end, Vanch “figures out who is close to me, and if I have any weak spots, and he tries to exploit them,” Amell says. For that reason (and perhaps another), Laurel gets targeted by the big bad. “You definitely see some more of the relationship betweenBetrayal Laurel and the Arrow, and you see a lot of betrayal going on,” Katie Cassidy shared. “I mean, this is a big episode for Laurel and there’s a lot of action and a lot of things happening.” The actress then echoes something Amell has hinted at, saying, “Yeah, there is a huge, huge ending that I am really excited about…. I think it might be one of my favorites.”

And what were Amell’s own words to tease the bejesus out of “Betrayal”? “I will say this. The ending of Episode 13 is season finale-worthy. It comes out of nowhere,” he enthused. “It is something that people have been waiting for, and it is one of those moments that end with people screaming at the television and clamoring for next week.

“It is the most [gasp-worthy] ending of the entire series, so far,” he added.

RELATED | TVLine’s 2013 Renewal Scorecard: What’s Coming Back? What’s Getting Cancelled?

As for milder-mannered Oliver’s own arc within the episode, he will show Moira his father’s notebook, which he got from Felicity (who got it off Walter), and question her about the names on the list. And that will likely put Mom in a pinch. “More suspicions are raised around her” — including and especially by Diggle, said Susannah Thompson. (Watch for a tense exchange ‘tween the two when he steps in as her driver for the night, and she ominously notes, “It’s a very dangerous city, Mr. Diggle.”)

And, as previously promoted, the episode also flashes back to Oliver’s very early island days, including his first meeting with Slade Wilson aka Deathstroke (played by Spartacus’ Manu Bennett).

All told, at least two major twists are on tap tonight — so if you think photos floating around from the next episode reveal all, think again. What are your predictions for “Betrayal’s” big bombshells?

Want more scoop on Arrow, or for any other show? Email mattmtvguy@gmail.com and your question may be answered via Matt’s Inside Line.