“Irreconcilable Differences” begins with Oliver and Thea walking with William at Oliver and Felicity’s wedding reception. Oliver is soon joined by Felicity and both of her parents.
Oliver and Felicity are busy talking to the various guests while Dinah, Rene, and Curtis are having drinks at the bar as they share their mutual dislike for weddings. Dinah gets a text from an unknown number and leaves the bar to respond.
Lance pulls Oliver aside and gives him a watch that his father gave to him on Lance’s wedding day. Curtis catches Felicity’s bouquet and proceeds to give a speech — whilst inebriated — before he’s cut off by Rene. Rene finishes out the speech before giving the couple a toast as they head to the dance floor for their first dance.
After they’re done, Lance accidentally bumps into Felicity’s mom and an awkward moment
Oliver and Felicity are discussing the possible mole when they’re approached by Diggle. Felicity shares that she’s running surveillance on Dinah, Curtis, and Rene — a move that Diggle doesn’t agree with.
Rene’s helping a drunk Curtis into his apartment. After settling in, Curtis starts talking about his past with his ex-husband and asks Rene if he thinks life would be any easier without Team Arrow. Rene’s in the midst of answering Curtis’ question when Curtis passes out.
Dinah’s talking to her ex-boyfriend Vince — a.k.a. Vigilante — in an alleyway. She tells him to stop contacting her, saying he needs to skip town or she won’t allow him to continue on as Vigilante.
Lance is walking Thea home after the wedding when the two are stopped by Black Siren; she brings the message that Cayden James wants to see them. She knocks both of them out before leaving a cellphone with Thea and taking Lance.
Back at Arrow HQ, Oliver, Felicity, and Diggle catch Dinah’s hallway talk with Vigilante. Oliver thinks she’s the culprit.
Thea walks in with the
At ARGUS, Diggle uses his relationship with Lyla to convince the security guard to allow him to get into her office. Diggle uses Lyla’s laptop to get a location on the amplifier, which the rest of Team Arrow — who is staked out around ARGUS — uses to get closer to the amplifier.
Oliver’s able to sneak into the amplifier’s room and take it without getting noticed, and the team heads back to their lair.
There, they discuss that the amplifier can enlarge the blast radius of Cayden’s thermonuclear bomb.
Dinah walks in and realizes the team just got back from the field and is upset she wasn’t called. Oliver tells her he suspects her as the culprit that turned Oliver into the authorities. In the ensuing argument, Diggle lets it slip that Oliver and Felicity have been surveilling Dinah, Curtis, and Rene.
Curtis takes Dinah’s side and is backing her up in the argument when Rene steps in and tells everyone to stop. When Oliver asks
Rene says he was approached by the FBI agents saying they had proof that he was Wild Dog, and in exchange for his testimony against Oliver, they’d let him walk. A furious Oliver orders Rene to leave the premises immediately.
At Cayden’s lair, Black Siren is questioning Lance about their standoff on Lian Yu. The two share a moment where they find out that even though they’re from separate worlds, they share very similar bonds.
Dinah and Curtis are speaking with Rene, trying to comfort him about his decision. Curtis and Dinah are still upset that they were being spied on.
Thea’s talking to Oliver, who’s having second thoughts about kicking Rene off the team — especially since he’d do anything in his power to make sure William was safe. Thea’s talk convinces Oliver to order Diggle to call in the whole team, including Rene, to help save Lance from Black Siren and Cayden James.
The team suits up and goes to the meeting point to make the exchange with Cayden James. Felicity mentions that the meeting location is a digital black hole where she won’t be able to see or hear them.
Oliver instructs Rene, Curtis, and Dinah to act as his eyes and ears while he makes the exchange. Oliver hands over the amplifier, but Cayden instantly recognizes that it’s been sabotaged. Cayden orders Black Siren to kill Lance while his henchmen try taking down Oliver.
Dinah comes to Oliver’s aid while Rene and Curtis go rogue and try to find Lance by themselves. Black Siren takes Lance outside, and, instead of killing him, she cuts his
The team rendezvous back at the lair, where Oliver asks Rene why
Dinah steps up and mentions she no longer believes in Oliver, and tells the group that she’s leaving the team. Dinah’s seen in a parking garage meeting up with Vince, telling him that she needs a friend.
Rene takes his daughter to his apartment and promises that he’s never going to let anyone split them up ever again.
Back at the lair, Curtis approaches Oliver, Felicity, and Diggle and tells them that he can’t trust them any longer, and leaves the team. Oliver tells Diggle and Felicity that they’ll still move forward.
The episode ends with Cayden rounding up all of the weekly villains we’ve seen this season, including Vigilante and Richard Dragon, revealing they’re all working together.