Giovanni Ribisi and Jason Lee have already signed and Myriad is expected to announce the female lead and more casting shortly.
David Michaels will direct from a screenplay he wrote with Phil Reeves about a graduate student who spends a summer on a remote island whose residents harbour a terrible secret.
Diane Isaacs will produce and Myriad chief Kirk D'Amico will serve as executive producer. Harrelson is represented by CAA and Michaels by the William Morris Agency. The project was packaged by Philip Alberstat at William Morris Independent.
Myriad's slate includes the Patricia Highsmith adaptation Cry Of The Owl starring Julia Stiles and Paddy Considine, political thriller Divided starring Diane Kruger, and sporting drama The Cup with Geoffrey Rush.