Cal and Becky Demuth are two inseparable brothers, being named Irish twins by their parents. Becky has been pregnant for the last year of college, and her parents suggest she go to live with her aunt and uncle until the baby is born. As it is spring break, Cal decides to accompany her on her journey, the two of them stop to visit many tourist locations along the way. After driving for about three days, they stop on a field with tall grass, where they hear a little boy, named Tobin, shouting for help. In these circumstances, the brothers decide to venture out into the field to help little Tobin, but he soon discovers that there is no way out and that something evil is hidden in the tall grass.