A very dangerous person named Cyrus Vanch has been let out of prison "on a technicality," according Laurel. That seems weird, since she's the sort of lawyer who's normally in favor of technicalities. But he's scheming for a way to take over the mob and the Triads, so she's probably right to be worried. So she calls her good friend the vigilante and asks him to round up some evidence that Vanch is up to something. Oliver gets the information, but he lets Vanch know he's there.
When Oliver gives his evidence to Laurel, the police are also there! This is because Detective Lance has bugged the Arrowphone, which you should have remembered. They don't get him, but Laurel now has a reason not to trust her father. Vanch somehow learns about it, so he kidnaps Laurel in an attempt to lure the vigilante to his house. Detective Lance can't trust his fellow police anymore, so he calls the Hood. Oliver kills a few dozen guards on the way in, but he won't let Lance kill Vanch.
Meanwhile, Diggle is concerned about the news that Oliver's mother had a notebook just like Oliver's. Oliver will not even consider the possibility that his mother could be involved in evil, even though he already knows that his father was a bad guy. He asks his mother about the notebook, and she immediately throws it in the fire. But that's not enough to convince him, so Diggle has to become Moira's chauffeur. He quickly finds a way to record her meeting with Malcolm Merlyn, in which they discuss shutting up an associate. They also talk about how she has the Queen's Gambit in a warehouse in Starling City because she knows it was sabotaged. Oliver has trouble dealing with that, but he eventually decides to go interrogate Moira as the Hood.
And in the past, Oliver finds a weird Australian on the island. His name is Slade Wilson and he's got the same two-color mask as the person who tortured Oliver, but he promises he's not the same guy. I'm pretty sure he's the same guy, though. He's going to train Oliver in the use of weapons so the two of them can assault an airfield.
We're back to having Oliver explain the show to us in the opening, so you know this isn't as important an episode as last week.
Iron Heights Prison. Someone's being let out and he's welcomed by a hot blonde with a sports car. Then the two of them arrive at a fancy house so the guy can talk to someone named George about all the criminal upheavals that have been happening like the Triad and Bertinelli getting arrested. Her name is Vivian. The man offers George a hug and asks for a place to stay. Then George dies, because the man stabbed him.
Arrowlair. Diggle recaps the duplicate notebook that Oliver's mother had. Oliver thinks his mother is a good person, but Diggle points out that Walter has mysteriously vanished.
Back on the Flashback Island, Oliver finds a wrecked airplane. A man drops through the ceiling and threatens to cut out his voice box. Oliver stammers that Yao Fei gave him directions and that's enough to make the guy pause. And they both pause for awhile until the scene's over.
Detective Lance protests to Frank (his superior) that he doesn't want another assignment, since he's working on the Hood case. Frank thinks not everyone wants the Hood caught, because he's been doing some solid vigilante work out there. That's kind of a weird position for the police to take, but I like the idea of Lance being the only one in town who wants to deal with the murderous vigilante.
Oliver walks in on his mother, who's getting ready to leave for something. It doesn't matter what it is. Oliver hands her the notebook he got from Felicity and says Walter gave it to him. Moira claims it's a list of people who owed Oliver's father favors. Oliver says all the people in the notebook are bad people and Moira decides the only way to keep the family safe is for everyone in it to stop asking questions. To make this easier, she throws the notebook in the fire. I'm not sure why there was a fire burning in this room's fireplace if Moira was about to leave, but I guess when you're rich you can have as many fires as you want.
Thea's at CNRI for her court-ordered stint of helping out. Another intern named Anastasia provides some exposition: someone named Cyrus Vanch got out of prison. And they do "victim advocacy," so they want him to stay in, because he murdered ever so many people. Tommy calls Laurel to ask her out to an audition he's holding for chefs to work in the nightclub, but she's busy.