Joining Emile Hirsch in Paramount's impending "Into the Wild" will be indie stars turned superstars Catherine Keener and Vince Vaughn. Sean Penn will be directing, and he's already penned the adaptation of John Krakauer's book.

According to The Hollywood Reporter: "Catherine Keener and Vince Vaughn are taking a walk on the "Wild" side. The two have boarded the Sean Penn-helmed "Into the Wild," which Paramount Pictures' new specialty division is distributing. Emile Hirsch already has signed on to star in the film, which chronicles the true story of Christopher McCandless, who graduated from college in 1992, abandoned his possessions and hitchhiked to Alaska to live in the wilderness and return to nature. He died four months later in an abandoned bus at a remote campsite. Penn adapted the screenplay from Jon Krakauer's book of the same name. Keener's character picks up the hitchhiker and takes him in as a surrogate son. Vaughn plays a tow-truck driver whom Hirsch's character meets on the road."