Sadie Sink, known for Netflix’s Stranger Things, is joining the cast of Marvel’s Spider-Man: Brand New Day in a “mystery” role opposite Tom Holland. Multiple outlets report that her casting is highly secretive: Sink did not audition for the part and did not receive or review the script until she arrived in London for filming. One account says the decision ties to a previous collaboration involving director Destin Daniel Cretton, which helped her secure the role without a formal audition. In interviews, Sink describes a positive on-set experience working with Holland, including that he is relaxed and welcoming, making her feel comfortable as she steps into the Spider-Man franchise. Details about her character remain undisclosed, and her appearance is not tied to visible marketing materials for the film, according to coverage that notes she has not been shown in trailers or promotional footage. The film is positioned as an upcoming MCU installment, with Sink’s role expected to be revealed as production continues and the movie approaches release.