Oliver is concerned when a mysterious illness sweeps the city, infecting hundreds of people, including Diggle. Oliver discovers Vertigo in Diggle's blood and realizes The Count has broken out of prison and is once again distributing his drug. Meanwhile, Moira goes on trial for her participation in the Undertaking. ADA Adam Donner collapses in court with Vertigo symptoms so Laurel must step in and try the case against Moira. Oliver is torn between standing by his family during the trial and catching The Count. However, things change when Felicity follows a lead and walks straight into a trap set by The Count.
A flu-like virus is spreading across the city and Digg is very ill. A blood test reveals trace amounts of Vertigo which Oliver traces to the Count, who escaped from prison during the earthquake. The antidote Oliver had previously used doesn't seem to be working. The Count seems to have found a way to get much of the city hooked. When he takes Felicity prisoner, Oscar sets out to rescue her - but the Count tells him he's not working alone. It's time for Moira Queen's trial but soon after it starts, the lead prosecutor collapses leaving Laurel Lance, who had been second chair, to take over the case. Someone from Moira's past reappears.
- We open "six months ago" with Moira speaking to reporters. She admits to being complicit in a plan to destroy the Glades and warns everybody to leave. We cut to the prison and see the guards leave without releasing any of the prisoners. The building breaks apart and one of the criminals is set free. The man grins and heads out into the chaos.
In present day Queen and Thea arrive for Moira's trial. One the steps of the courthouse Adam tells Laurel he has something special on Moira.
We flash back to the island. Ivo and Sara bring Queen to his hideout he shared with Slade and Shado, but nobody is there. Ivo sets an explosive, then tells Queen to take them to the graves. They leave and we see Shado disconnect the bomb. The two of them go after Queen.
In court Moira's press conference is played for the jury. The prosecution thinks her second thoughts aren't enough to keep out of prison. Her defense makes the case that she showed strength in the face of a terrible situation.
Digs is sick and Felicity advises him to go home. While he works on arranging his replacement for the day he collapses.
The criminal from the opening makes a transaction with a doctor, afterwards injecting something into his shoulder.
Felicity has found traces of Vertigo in Digs' system. They figure out that the Count must have escaped from prison during the quake and brought Vertigo back to the city. Queen gives Felicity something to help Digs and leaves to get the Count.
While Thea is on the stand Adam asks her about blaming her mother. Afterwards he collapses and falls to the ground.
Back on the island Ivo is upset they can't find the arrowhead where the bodies were found. Just as they threaten to shoot Queen, Slade and Shado arrive to save the day.
Queen tells Moira she needs to testify. He thinks it's time to "give the truth its day."
The antidote didn't work with Digs, meaning the Count must have altered his recipe. The Count jumps on local TV with a very drug sick Adam by his side. He says the cure for what ails the city is more Vertigo, advising them to seek out their local drug dealer to end the pain. Queen thinks the contamination must have been selective somehow.
The DA tells Laurel she's replacing Adam as lead counsel. While going through his notes she finds his "trump card."
Roy gives Thea some boxing gloves and tells her to hit him in order to get out of some of her rage. She starts pounding his chest and begins to cry.
Felicity finds evidence the Count is operating out of the old city records building.
Laurel visits Moira in prison. She's heard Moira will be taking the stand and Laurel advises against it. She shows Moira a folder and tells her she doesn't want to be the one "to take it all away."
Arrow arrives at the Count's production facility. He rescues Adam but passes on killing the Count.
Moira tells her children that Laurel has the entire truth. She tells them she cheated on their father with Malcolm Merlyn.
Cut to Moira being cross-examined by Laurel, who makes the point that since she and Malcolm had an affair her family wasn't really in danger.
Outside of the courtroom Queen wants to make sure Laurel's okay. She doesn't understand how he could forgive her.
Back on the island Ivo wants to exchange the arrowhead for Queen. Queen is cut loose and a firefight ensures.
Felicity figures out that the drugs were administered via a roving flu truck. With Queen busy and Digs sick, Felicity goes to check it out. Felicity goes to one of the truck and finds the Vertigo. Unfortunately the Count is waiting for her.
Moira's lawyer tells Queen and Thea to "prepare for the worst." The Count calls Queen and tells him he has Felicity and knows that he is the Hood. Queen leaves.
Queen goes to see Count sans hood. The Count tells him someone of means set him up in order to draw Arrow out. The Count places two syringes of Vertigo at Felicity's neck and Queen kills him in order to protect her.
Queen returns to the courthouse in time for the jury coming back with a verdict. She's found not guilty of all charges. Laurel, Queen and Thea all look stunned.
Queen tells Felicity and Digs that the verdict doesn't make sense. Felicity apologizes for putting him in the position to kill again.
Queen and Sara tell Shado what Ivo is looking for. She has it, and they see on the back there are coordinates. Sara says it's too a sunken Japanese submarine, that contains something which could save the human race. Queen wonders if it could also help Shade, who looks near death. A disappointed Ivo kills the captain.
We see that the Alderman was the one behind the Count. He puts on his Brother Blood masd and goes to a dark room. He finds a man named Cyrus and asks him how he feels. "Stronger," Cyrus says. "Good," Brother Blood says. "They you're ready."
Moira is brought to a parking lot. She meets Malcolm, who is very much alive. He tells her he was behind her acquittal. He says he's learned that Thea is his daughter.