So sort of an accidental parent trap thing where the Leverage crew is going after an artifact because the guy who owns it swindled it from their client, with Elliot playing the part of an art historian. But it turns out the artifact is a magic item and the LiTs are trying to get it for the library. Accidental switch up when they see Elliot in character and think he's Jacob and Elliot plays along because he doesn't know how to extricate himself from this peacefully. (Cont)
(cont) Meanwhile the Leverage team think Jacob is Elliot (and has really done his research for the role) and Jacob is playing along because he's might curious why these people think his long-dead brother is alive and working for them. Long story sort Elliot learns magic is a thing, Jacob finds out his brother is alive, and both crew are like 'You could have mentioned you had a twin'. Leverage crew possibly gets hired as retrieval specialist for the Library.
(cont) Bonus: Parker knows right away that Jacob isn't Elliot because he moves wrong, but no ones else believes her till the reveal. She is VINDICATED afterwards.
Everyone please read this, it is delightful.