We get a lot of backstory about the Undertaking and what led to the sinking of the Queen's Gambit. The Vigilante kicks some serious booty, Tommy has another talk with Laurel, and someone returns.
Turns out that the Undertaking (in its current form) is not that old. It was proposed by Malcolm shortly before the fateful voyage of the Queen's Gambit. Before that Robert and several other people had decided to do what Oliver is doing and clean up Starling City one person at a time. Malcolm decided that the best thing would be to completely wipe the Glades out and start from scratch, in no small part because his wife was killed in the Glades. Somehow, Malcolm was planning on getting a piece of technology that would allow him to make the whole thing look like a natural disaster.
Robert was not happy with this idea and plotted with Frank Chen to buy up enough of the Glades to force Malcolm to give up his plan. This was after he told Moira about the proposal and she reacted in horror. So Chen went to supposedly fly to China while Robert would take his boat. Oliver decided at the last minute to come along and took Laurel's sister along with him- probably because Laurel wanted to move in together. Chen planted the bomb as instructed by Malcolm, and the rest is history.
What I found interesting is that Moira blames herself for what happened. That is understandable, because Robert rebelled openly in large part because of her reaction. Not that he didn't have his own doubts already, but I do not think he would have moved as openly as he did without knowing Moira's reaction. Her reaction when Oliver (mistakenly) said that Walter was dead was pretty much what I expected. Anger and surprise because of the fact that Malcolm had promised not to hurt Walter.
I was definitely shocked that Oliver decided to follow Moira. I don't know if it was her reaction to what he said or if he was suspicious for another reason, but following her seemed a little odd. It did let him know that Malcolm had Walter, that Moira knew this, and that Moira was working with Malcolm. Given the look on his face, none of this was welcome news. Loved the rescue of Walter. That was just awesome. An incredibly brassed-off Oliver against 20 (or so) guys? They never had a chance. When Oliver is motivated, he is motivated and can accomplish almost anything. I do wonder if Walter figured out his secret, because Walter was giving Oliver an odd look when he was in the hospital.
Poor Laurel got two punches to the gut tonight. First, Tommy tells her that he broke up with her because she and Oliver belong together and because Oliver still loves her. So, she confronts Oliver and asks him to tell Tommy that he is not in love with her, only to have Oliver tell her that he won't lie to Tommy. That poor girl is going to need some serious alone time so that she can figure things out.
Loved Felicity tonight. Between going to Diggles to help him and Oliver make up, going into the casino to help find Walter, and then helping Oliver plan how to free Walter, Felicity did a lot of good stuff. Also loved that Oliver and Walter both called her "a friend". She was very happy to hear that. Glad that Diggles and Oliver made-up because they will both be needed to combat the Undertaking.