Watch on SFlix. Nineteen-year-old Sersha Cleary is struggling with adulthood and mental illness when she experiences a harrowing coincidence. Three knocks and a bone-chilling scream hours before her grandmother passes. The signature of a banshee an Irish myth her grandmother told her stories about when she was little. After her grandmother passes Sersha finds herself alone and struck with intense grief, fighting with her family and struggling with her everyday life. Amongst her struggles she finds herself haunted by a banshee unable to escape its grasps.