The episode's secondary arc at A.R.G.U.S. initially felt like it was nothing more than, well, secondary. After all, John Diggle needed to feature in the episode and there had to be some sort of mystery storyline, right? So, it almost felt like an obligatory way of including all of this. Thankfully, it managed to become so much more than just that.
Curtis was recruited by A.R.G.U.S. for a special mission that would see him taking part in a chemical deal. The former vigilante was already working for the organisation as a tech-guy, but he was appalled at the idea of going out into the field on a covert mission. While this refusal, at one point, just sounded like typical Curtis babble to delay the inevitable, he eventually revealed that he was fearful of ever going out into the field again, rebuking the crime-fighting lifestyle for what it had taken from him in the past.
His emotional struggles added a unique layer of doubt that we don't often see in the show's weekly capers and it gave a character that is often written off as a caricature something deep to overcome - which he did exceptionally well. It was nothing short of glorious to see him successfully disarm a bomb and take out armed men before his backup even arrived. In that moment it was clear: Mr. Terrific was back.