After putting Vandal Savage down last week, Arrow dives into "Dak Waters" in its midseason finale and leaves us with a bang.
It all begins with people picking up the trash from the bay, when a toy helicopter starts shooting them and Felicity puts it down. Oliver knows it’s Darhk and feels bad about the innocent people, while he thinks they can get Andrew to talk. A flashback finds him telling Taiana to teach him how to dive so they can beat Reiter. Back to the present, John confronts his brother and asks what Darhk wants with the bay, but Andrew claims he doesn’t know. Donna has given Oliver’s campaign office a Christmas decoration and finds the engagement ring he planned on giving to her daughter, showing it to her. Oliver talks to the media and puts Damien Darhk’s name out there along with HIVE. Darhk breaks down a TV and is ironically congratulated by one of his colleagues. At the lair, Oliver wants to cancel the holiday party but everyone is against it. Oliver asks Felicity if their move was right, and she says they’ll be prepared when Darhk hits back. In another flashback, Taiana is taken to some shore and handed a map to help with Oliver’s plan.
Malcolm visits Thea to say her effect on Darhk is something they fail to understand, which scares him, but she’ll take care. At the party, John has brought the Marines for security and Felicity hears Curtis’ engagement story and looking for her mom. She finds Donna making out with Quentin and once he’s gone, she says Oliver was planning to propose three months ago. Things have changed since they moved and she asks if he changed his mind, hoping they can get the best of both worlds. Darhk interrupts and wants to punish Oliver by throwing him away and kidnapping his beloved ones. He promises to get Felicity, Thea and John back and starts going after Ghosts to locate Darhk, despite Laurel trying to talk some sense into him. A flashback finds him swiming to some old and treasury ruins. The present finds Laurel confronting her father over working for Darhk, but he says he’s been working for Oliver lately and both get a text to meet him.
They gather at the lair and Malcolm appears with a phone that can contact Darhk, while Oliver wants to turn himself in to save the others. Darhk’s colleagues complain about wasting time on Mr. Queen, when he does offer himself. Darhk shows Oliver his experiment of putting volunteers into a gas chamber for tests and kills a guy that way while at it. Laurel prepares to go save Oliver and Lance wants to join, but she makes him stay back. Oliver’s walking through cells and they let him inside Felicity’s, who confronts him for turning himself in and things get intimate when she says she’d have said yes to the proposal. In yet one more flashback, Olliver finds a map and swims back to the shore. Real time, Darhk’s minions get Felicity and the others dragged into the gas chambers and when all hope is gone, the Black Canary appears with Malcolm as the Green Arrow. Laurel uses the Canary Cry to get the ghosts down and break the glass of the chamber, with Merlyn going after Darhk before leaving.
Merlyn is almost psychically strangled before Oliver interrupts. As team Arrow’s making an exit, the cells open and ghosts are after them, so thankfully Lance shows up with a bunch of cops to help them take everyone out. Darhk is punching Oliver when Malcolm gets him with his arrows and leaves an explosive one as they head out, with Damien saying some mystical words. At the lair, everyone’s happy but Laurel hints that he might not stay dead, while Thea and Felicity have a surprise. The last flashback finds Oliver returning to the shore with three guards waiting for him. In the present, Andrew is not cooperating at all while HIVE is disappointed in Darhk. However, he’s happy and takes them to a corn field, where the air he created is breatheable. Oliver is taken to make good with the citizens and light up some tree, but he also proposes to Felicity and she says yes. They drive away in a limo, when ghosts shoot down the car. He manages to drive away, while Darhk spends Christmas with his family, but when they’ve lost the ghosts, Oliver finds Felicity seeming dead.
Now "Dark Waters" was a midseason finale with one hell of a cliffhanger! Didn’t Barry and Oliver seem rather calm over that grave for the deceased one to be Felicity? No matter what, we won’t be missing a single second of Arrow when it comes back.