When one of alt!Magnus' spells goes off course, he finds himself in a universe where another version of him is working as the High Warlock of Brooklyn and is in a stable relationship with shadowhunter Alec Lightwood. Together, the three of them have to figure out how to send him back to his old dimension.
He's just not sure how he's going to break the news that he and Alec aren't together in his universe.