In THE WHOLE TRUTH, Mai (Nicole Theriault) is a single mom raising two teens, the cheerleader Pim (Sutatta Udomslip), and Putt, an aspiring artist who's bullied for having a leg brace. One night while driving home late from work, Mai gets into a head-on collision with a drunk driver, and suffers a concussion and coma. Pim and Putt learn the news from their grandfather, one Mr. Samphong, who they've never met until that moment. While Mai remains in a coma in the hospital, Pim and Putt are sent to live with their grandparents, including their grandmother Wan, who is in the early stages of dementia. Soon, strange things begin to happen. Wan keeps forcing Putt to drink large glasses of milk, resulting in a recurring bloody nose and feelings of nausea. One day, they discover a hole in the wall of their grandparents' apartment. Putt looks inside, and sees a demonic baby vomiting torrents of blood. Their grandparents claim not to see the hole. The more Putt looks into the hole, the more he sees what seems to be an alternate reality, and their grandparents continue to deny what Putt and Pim are seeing. When Mai comes out of her coma, it's up to her to find a way to escape the hospital, confront her parents, and reveal to her kids the tragic and horrifying reality about what really happened in her past, and how it's being revealed through the hole in the wall.