In the Tall Grass is a horror novella by American writers Stephen King and his son Joe Hill. 

Cal and Becky Demuth are inseparable siblings (being called Irish twins by their parents, although they are 19 months apart). Becky finds out during her sophomore year of college that she is pregnant, leading the twins' parents to suggest she go live with her aunt and uncle until the baby is born.  While on this journey brother and sister enter a field of tall grass to rescue a boy, but they soon realize they cannot escape and something evil lurks in the grass.