Jason Segel (Forgetting Sarah Marshall) will be joining Jonah Hill and Jason Schwartzman for The Adventurer’s Handbook for director Akiva Schaffer (Hot Rod). The actor is attached to the film, based on the book by Mick Conefrey with the script from Hill and his writing partners Max Winkler and Matthew Spicer. The trio sold the script back in February to Universal, after it was sent over to Hollywood’s top studio heads on red, watermarked paper. The project centers on four 20-something guys, who inspired by a book of the same name, set out overseas in search of a mysterious location described in the book. R-rated in tone, the film is still in development and doesn’t yet have a greenlight or a start date.