Intro is about how Goetia knew humanity would end in 2016 but couldn’t figure out why, so he enacted his own plan.
Dr. Jekyll and Holmes were aware of each other in life and Jekyll wants to get to know him better at Chaldea. Guda is like “wait Holmes was a real person?” and Holmes kinda dances around the question, clearly not wanting to talk about his past. Mashu ignores him being shady and says “wow so there could’ve been Sherlock vs Jekyll IRL that’s so cool”
We find out Mr. Hyde was engineered by Moriarty via him making the ingredients for the transformation potion difficult to find. This was mentioned in Holme’s materials, but it’s the first Guda and Mashu are hearing of it. We don’t get more than this because Jekyll thinks talking about it will make Hyde come out and asks Guda to move the conversation along.
Holmes says that he knew about the existence of the Clock Tower in life but wasn’t able to interact with it much. Apparently, “The Adventure of the Speckled Band” was actually magical in nature.
Reenactment time! Watson is represented by Gordolf, which he initially finds insulting but remembers that Watson was played by Edward Hardwicke in the 80’s TV show, so it’s cool.
Details on the case: rather than the speckled band being a snake, it’s actually a curse, which shows up as a hydra you have to solo with Holmes. The reverb kills whoever the caster was.
Watson self censors this bit when he writes the book so the Clock Tower doesn’t get mad. This censoring of magic into non-magic happened several times. For example, the dog from Hound of the Baskervilles was related to the Storm King/Wild Hunt. Holmes jokes(?) about turning this into a movie with help from Edison and Mashu loses it fangirling.
Helena shows up and talks about her history with Holmes. During his “blank period” from 1891-1894 after his faked death with Moriarty, he was in the Himalayas with her. This is elaborated on in Chaldea Ace, can’t find the translation but I’m sure it’s around somewhere. The TL;DR is that Helena’s research into spirits is threatening the stability of the Clock Tower, and someone has sent assassins after her. Holmes was with her, attempting to protect her.
Afterward, Helena straight up asks if Holmes is a rogue servant or if someone summoned him. This surprises the “shady gentleman at the edge of the screen.” She continues, trying to ask how he got to Camelot, when said shady gentleman, Moriarty, jumps in and physically muffles her.
Holmes and Moriarty immediately start arguing, with Moriarty going so far as to call Holmes out for pretending to be an ally of justice (yes, seigi no mikata) when he’s supposed to be an impartial Ruler-class servant, as Holmes said in his trial quest.
Holmes fires back with “you screwed with the mainframe, Brynhildr, Mecha Liz, etc, what are you trying to accomplish?”
They argue so hard back and forth that Jekyll almost turns into Hyde, and Helena makes them take their argument to the simulator. Moriarty makes sure to give Jekyll the extra push, and Hyde comes out full force, ready to fight. You beat them both up.
After the fight, Moriarty just snaps his fingers and Hyde is back to Jekyll. He then smoke bombs and runs.
Holmes asks us if we ever wondered why he was a detective. When we ask, he says it’s because of justice! He is truly an ally of justice, it’s his motivation. Even with the Lostbelts forcing us to commit crimes, in a way, we’re in a battle for survival and we’re definitely still the good guys.
Helena and Holmes are alone afterward, and she asks if he has some secret. He replies that everything he said was true, he is an ally of justice, but he also has secrets even he doesn’t fully understand. Helena puts two and two together and asks if his committal to justice might make him do evil, or even go against Guda. He says she’s wrong, but then says that he’s firmly on the side of humanity, without directly mentioning Guda.
He swears it’s true, and she asks what he would be swearing on, God? He replies that he’s swearing on her beautiful last moments in the Himalayas, and another flashback starts.
An assassin mortally wounds Helena, and Holmes pulls him off and attempts to kill him. Helena yells to let him live, so Holmes just knocks him unconscious. He recalls that she asked him not to kill anyone that came for her, as she was already old, and someone her age killing young people seemed morally wrong. She holds his hand as she dies, seeing a silverly light coming to take her to the sea of stars.
Cut to present, and Helena asks him why he was mumbling, and what he would swear on. He says it shouldn’t be repeated, and the interlude ends with him laughing, her extremely confused, and Fou kicking his head.