James Marsters will star opposite Hilary Swank and Gerard Butler in the drama, P.S., I Love You for Alcon Entertainment and Warner Bros. Pictures.

Directed by Richard LaGravenese, the film is based on the best-selling Cecelia Ahern novel about a grieving young widow who discovers her late husband has left her a list of tasks revealed in 10 monthly messages that are intended to ease her out of grief and transition her to a new life. The Hollywood Reporter adds Marsters will play the late husband's best friend.

Production on P.S., I Love You begins next month in New York and Ireland; a 2008 release has been set.