When lonely single mum Janey stumbles into an art workshop, she can't believe her eyes when her left hand mysteriously scribbles a picture of two little girls and a message from someone called 'Hattie': Janey's childhood best friend who she lost touch with after Hattie's family suddenly moved away in mysterious circumstances. Janey's instincts tell her that she must finally find out what happened to Hattie, but when writing appears on the walls of her flat and her son Pip starts playing with an invisible friend, Janey fears she's losing her mind. Is it really a good idea to go digging up the past? As dark secrets come to light, she can't be sure what's real any more—or who to trust.