The time is quick drawing closer for the Undertaking to happen and Malcolm Merlyn starts to clean up the last details, starting with the researchers at UNIDAC. Oliver and Digg stunt Moira into mentioning to exactly what the Undertaking is about. Oliver understands that regardless of whether he figures out how to kill everybody on his dad's rundown he has just, in his own words, dispensed with the side effects and not the infection. Felicity finds the UNIDAC gadget - kind of. Thea and Roy's relationship comes to head when they can't find the vigilante. Walter seeks legal separation. Tree and Oliver start a ...