Frederick Langlois could be that geeky 17-year-old found in every high school -- the one who closely clutches his poem-filled notebook, who feels a bit too deeply, who's just a little too old for his years. But Frederick isn't in high school. He's in a hospital ward with other critically ill adolescents, dying of bone cancer. Mercury Under the Tongue chronicles his short stay there, from his distant but friendly relationship with his therapist through...