When critically ill Jacob Wilson is given a life-saving heart transplant, his parents are relieved that their loving son has been saved.However, before long, his family are forced to accept that something has changed in Jacob. Their once loving son is slowly being replaced by a violent man whose mood swings leave them terrified - but is it their fault?Jacob's girlfriend, Rosie, is convinced the man she loves is suffering from stress. But when his moods turn on her, she begins to doubt herself - and she can only hide the bruises for so long.When a terrible crime is committed, Jacob's family are forced to confront their darkest fears. Has the boy they raised become a monster? Or is someone else to blame?