Now that Spider-Man: Brand New Day has finally revealed Sadie Sink's mystery role, Marvel Studios boss Kevin Feige has shared why the comic book movie company fought so hard to keep it a secret. Spoilers for Spider-Man: Brand New Day follow. Sink plays… Jean Grey. The new Spider-Man movie defied expectations by breaking records at the box office following its July 31 premiere. What do you think the Spider-Man: Brand New Day post-credits scene means?