"The Devil's Greatest Trick" begins with Cayden James speaking with Oliver and Diggle via a computer screen. Cayden
Oliver and Diggle go back to Arrow HQ, trying to brainstorm and act on a plan within four hours.
Cayden's addressing his henchmen about the final planning for the detonation of the bomb. He reminds them that they'll all be airlifted out of the city before the bomb is detonated.
In a flashback, Cayden is working at his computer at Helix. He's introduced to Felicity's hacker friend Alena. Cayden gets a text from his son; he's upset that his father missed his game.
Present day, Lance is trying to organize evacuations out of Star City.
Anatoly, Richard Dragon, and Laurel are discussing whether they trust Cayden. Dragon mentions that the airlift Cayden promised has yet to show up.
Dinah has converged on one of Cayden's safehouses with Curtis and Rene. She's looking for more information on where to find Black Siren in an attempt to get justice for Vincent.
Alena's helping Felicity at Arrow HQ. She announces that she uncovered the truth behind the video that framed Oliver as the murderer of Cayden's son. Somebody overlaid Oliver's face on the video that was supplied to Cayden.
Oliver and Diggle track Cayden down and show him the proof. Cayden realizes someone within his own organization orchestrated the death of his son.
The pair returns to Arrow HQ and tells Felicity and Alena that Cayden has ordered them to turn in Anatoly, Dragon, and Laurel, otherwise the bomb will still detonate. Thea arrives at the lair with William.
Realizing they need more help, Diggle calls Curtis and Rene to ask for their help.
Elsewhere, Dinah has tracked down Black Siren. The two begin fighting when Lance runs in to stop the fight. Dinah knocks him unconscious, and Oliver walks in and uses a restraining arrow on both of the metahumans, telling them he needs to save the city.
We see another flashback, one in which Alena warns Cayden that ARGUS has his "scent" and could be tracking him due to his hacking capabilities.
Present day, the group is holding Black Siren at their new Helix compound. Lance walks in and has a disagreement with Dinah about killing Laurel once they rescue the city.
William is growing frustrated with Felicity at the Arrow HQ, and she reassures him everything will be alright.
Oliver and Diggle track down Anatoly and make quick work of his henchmen. They capture Anatoly while Curtis and Rene catch Dragon.
At Arrow HQ, with all of the adults busy trying to get the three captured villains to Cayden James, William escapes the lair.
Oliver and Diggle take Anatoly to Cayden, and William shows up.
We see another flashback. Cayden is watching his son's basketball game from afar when two ARGUS agents show up to arrest him.
Dinah and Lance take Laurel to Cayden's facility. While Dinah goes to scout the place out, Laurel and Lance argue about the treatment of one another. Laurel feels that Lance has been far out of line, showing her pictures of his recently killed daughter.
They take Laurel
Black Siren steps forward and admits to killing Cayden's "stupid kid."
Back at Arrow HQ, Felicity and Alena notice something is wrong with Cayden's bomb and try to figure out what's going on. They realize that Cayden's bomb detonator is interfering with Laurel's power-dampening collar. Laurel realizes this and is able to rip the collar off.
She makes quick work of distracting everybody with her powers so she's able to escape. Immediately outside of the warehouse, Dinah stops her.
Inside, William sees the detonator on the floor and starts walking towards it. A firefight breaks out indoors.
Outside, Lance tries pulling Dinah and Laurel apart, but Dinah's able to shoot Black Siren in the stomach.
Cayden takes the detonator from William and tells Oliver that he feels that he failed his son, so he still plans to raze the city.
Oliver's able to shoot Cayden in the arm, making him drop the detonator.
Team Arrow is back at the Arrow bunker after being able to apprehend Cayden. Rene and Curtis remind Oliver that even though they worked together to take down Cayden James, they're going to remain separate teams.
The next day, Oliver walks in to speak with Cayden in an interrogation room. Oliver wants reassurance that being captured wasn't part of a ploy. To prove that he doesn't have any ulterior motives, Cayden gives Oliver a sheet of paper with potential locations for his former colleagues and their respective bank accounts.
In another flashback, we see an ARGUS agent tell Cayden about the passing of his son.
We see Lance has taken Black Siren to his car to help her out with the gunshot wound.
Richard Dragon walks into the room Cayden is being held in. After telling him Star City is prime for a takeover, Dragon reveals that the new police captain and a few other city officials are on his payroll.