Triangle is a 2009 psychological horror film written and directed by Christopher Smith and starring Melissa George, Michael Dorman, Rachael Carpani, Henry Nixon, Emma Lung, and Liam Hemsworth. George portrays a single mother who goes on a boating trip with several friends. When they are forced to abandon their ship, they board a derelict ocean liner, where they become convinced that someone is stalking them. The screenplay is partly based on the story of Sisyphus, the Greek mythological figure cursed to repeatedly push a boulder up a hill without ever successfully reaching the top.