'Arrow' Midseason Finale Trailer Reveals A Betrayal After The Wedding

"Crisis on Earth-X" may only have ended last night, but The CW is already looking ahead to the midseason finale for the Arrowverse shows. Today, the network released a new promo for "Irreconcilable Differences", next week's midseason finale for Arrow.

Still fresh from the conclusion of "Crisis on Earth-X", the newly-married Oliver Queen (Stephen Amell) and Felicity Smoak (Emily Bett Rickards) return to Star City to celebrate with their friends and loved ones, but as you can see in the video above, the joy is short-lived.

Someone on Team Arrow is willing to testify against Oliver in his upcoming trial on federal charges connected to him being the Green Arrow. If that wasn't bad enough, Quentin Lance (Paul Blackthorne), who informs Oliver of the rat, doesn't know which team member it is and from the looks of things that team member isn't talking. The promo shows Oliver going out into the streets with the rest of Team Arrow (sans Diggle, who isn't field-worthy due to his shoulder injury), but it doesn't look like he's quite getting the unified backup Green Arrow has been used to.

While not shown in the trailer but revealed in the synopsis for the episode, a surprise betrayal by someone on the team isn't the only thing Oliver and Team Arrow will have to face in "Irreconcilable Differences". Black Siren (Katie Cassidy) and Cayden James (Michael Emerson) kidnap Lance in an attempt to trade his life for a weapon of mass destruction. Somehow, the fracturing team will have to find a way to save Lance and Star City.

While it sounds like a tall order, it may also provide for an opportunity for audiences to learn more about Black Siren's backstory. Cassidy told ComicBook.com's Russ Burlingame at San Diego Comic-Con earlier this year that the Earth-2 villain's history will come into sharper focus this season on Arrow and some questionable quality time with Lance might just be the perfect opportunity.

"Yes, I think the more we learn about her backstory and what her relationship was like with Oliver, absolutely," Cassidy said. "I think it will make sense in the end and not necessarily make her as bad of a person. You might be like 'Oh, okay that makes sense.' Yes, I do think we'll know more."

Arrow airs Thursdays at 9/8c on The CW.