13 Reasons Why star Katherine Langford to star in fantasy sci-fi film Spontaneous 13 Reasons Why star Katherine Langford is set to star in the fantasy sci-fi film Spontaneous, according to Deadline. The film will be based on the young adult novel “Spontaneous” by Aaron Starmer. The book was a Time magazine Top 10 YA & Children’s Book for 2016 and an ALA Best Fiction for Young Adults selection. Spontaneous comes from writer/director Brian Duffield, writer of Insurgent, Jane Got a Gun and The Babysitter.