The episode opens with Felicity at physical therapy with Oliver and Curtis's husband, trying to take her first step out of the wheelchair thanks to Curtis's spinal implant. However, Felicity can't get her legs to function and she stumbles back into the wheelchair. Curtis's husband tells her about how all Curtis wanted was results when he first went to physical therapy for tendonitis, but that these things take time.
Oliver tells Taiana about Reiter's plan to kill everyone before Reiter collects them both to watch as his plans come to fruition.
After physical therapy, Oliver asks Felicity if she's okay. Felicity puts on a brave face, but she starts to tear up when she says she wanted to walk down the aisle on their wedding day. Damian interrupts their tender moment and gives him an ultimatum: pull out of the mayoral race by 6 PM on Friday or William gets it. When Damian leaves, Oliver finally reveals to Felicity that he has a son.
Back at the Arrow Cave, Felicity is understandably upset about Oliver hiding his son's existence a secret. The rest of the gang arrive at the Cave and get filled in on Darkh's ultimatum. As they start making plans to find William, Felicity finds out that Thea, Malcolm and Barry all know about William too.
Samantha arrives at Oliver's mayoral headquarters, frantic about William's disappearance. When Samantha asks what Oliver can do to find William that the police can't, Oliver tells her that he's the Green Arrow. Oliver takes Samantha to the Arrow Cave and introduces him to the rest of the team. After Samantha apologizes to Laurel for sleeping with Oliver while they were still together, the team tries to figure out how to bring down Darkh once and for all. Diggle suggests bringing Constantine in, but he's literally in hell, so Oliver suggests bring Mari McCabe in instead. Mari has a magical totem that gives her powers, and she goes by the name of Vixen.
In Detroit, three goons flee in terror and fire into the air as they're followed by a bunch of animal noises. Vixen takes out two goons, but Oliver shoots a third when he sneaks up on her. Mari asks if Star City was too boring for him, but Oliver admits that he came to Detroit for her help.
Oliver brings Mari back to the Arrow Cave and introduces her to the rest of the team. He explains that he and Mari had an...ANIMATED encounter last year and have kept in touch since. Samantha asks how Mari can find William, and Vixen explains about how her totem can summon the "spirit" of any animal. Mari takes one of William's Flash action figures and sniffs it and determines that he's somewhere in Star City.
Reiter shows Oliver and Taiana a hole in the wall of a bunker and says that he can feel a "primordial" energy radiating from it. That energy suddenly possesses one of Reiter's soldiers, causing his eyes to go totally white.
Thea calls a meeting with Malcolm, who's still mopey about losing his hand and the League of Assassins. Thea asks Malcolm if he told Darkh about William (he lies and says no) and pretends to be hurt that Thea asked him.
Vixen starts her search for William while Oliver and Diggle have a heart to heart about Oliver's newfound fatherhood. Diggle tells him not to stress about the past and to focus on finding William. He gives him a pep talk about keeping his children safe.
Meanwhile, Samantha tells Felicity that she was the one who made Oliver choose between spending time with his son and telling Felicity.
Laurel and Quentin coordinate the police search, and Laurel admits that it stings that Oliver knocked up another girl while they were dating. She gets a text from Oliver saying that they know where William is being held.
Team Arrow breaks into one of Darkh's penthouses, but Darkh reveals that he just moved William minutes before they arrived. Darkh tells Oliver that he can't win in a fight with him, but Vixen rushes in through a window and attacks Darkh. Darkh's magic gets the upper hand on Vixen at first, but she uses her own abilities to break free and fight back. Darkh tosses Oliver through a window to escape and although Vixen catches him, she says that she suddenly can't track William.
The team return to the Arrow Cave, where Darkh calls Oliver and tells him to move up his timetable for dropping out of the race. Mari says that Darkh must have a source for his powers, and Quentin admits that he's seen Darkh in front of an "idol" at his headquarters.
Reiter locks Oliver in with the ghostly guard, but the guard lets Oliver pass as Oliver's side tattoo begins to glow.
Oliver holds his press conference and suspends his campaign. He also endorses Darkh's wife Ruve Adams.
The next morning, Oliver and Alex pack up their office. Alex asks for an explanation, but Oliver can't tell him the truth. Felicity comes in as Alex leaves and Oliver admits that he handled the William situation poorly.
Mari tells the gang that one of her contacts recognized Darkh's idol and said that it needs to be near a lay line ("WiFi with magic") to work. Samantha also asks why Damian hasn't returned William. Oliver confides to Mari that he's worried that Damian is going to double-cross him again and Mari says that Oliver should consider letting William go to let him live a normal life.
Felicity traces Darkh to a compound outside the city, but Darkh calls Oliver and says he'll meet Oliver in three hours at Nelson Plaza with William. Oliver asks Samantha whether they should wait for Darkh to deliver William or try to take Darkh and his idol out, and Samantha tells Team Arrow to take Darkh down.
Team Arrow breaks into the compound, with Vixen, Thea and Oliver confronting Darkh directly. When Darkh starts force-choking Oliver and Thea, William comes out and tells Darkh not to hurt them. Vixen uses the distraction to smash Darkh's totem, leaving him powerless and open to a beating from Oliver. The team leaves as the police arrive to "rescue" William and arrest Darkh.
At the police station, Samantha hands William his Flash action figure, but William says he wants a Green Arrow figure instead. Meanwhile, Quentin tells Oliver and Thea that William said that it was a man with a missing hand who took William, not Darkh.
After the ghost disappears, Reiter hands Oliver a flashlight and tells him to enter the hole in the wall, which leads into a massive cave.
Outside the police department, Oliver thanks Mari for her help and tells him that she was grateful that her parents gave her freedom by giving her up for adoption...and the totem. She tells Oliver to call if she needs anything.
Thea confronts Malcolm about her role in William's disappearance. She tells Malcolm she's fed up with his lies and that she wishes she wasn't her daughter. Malcolm lashes back at Thea and says that he'd rather her be alive and hate him then dead.
Oliver records a note to William explaining that he's the Green Arrow and that's why he wasn't involved in his life. He says that he was responsible for him moving away and that he told his mother to give him the message on his 18th birthday. After he's done recording, Felicity comes in and hands him back his engagement ring. She says that she needs space and that Oliver doesn't know how to rely on his partner for help. However, Oliver notices that Felicity's legs have started working and she amazingly gets out of her chair and begins walking...right out the door.