In Ebensee, the teenagers Nina, her boyfriend Martin, Clemens, his girlfriend Alex and Mona are best friends since their childhood. On their high-school graduation day, they all receive the same text message, "In three days you will be dead!", but they believe is a stupid joke from their weird schoolmate Patrick. However, when Martin is found dead in the Lake Traunsee, the group realizes that it is not a prank. When Nina is attacked and Patrick is killed trying to save her, they recall a tragic incident from their childhood.