Battles of Sleep and Wake

People have nightmares. They're normal. But what do you do when you can't wake up? You have to experience what you fear most each and every night, only waking up when you accept your fate. A small group of people decide, after hearing so many others experiencing the same phenomenon, to find the cause of such night terrors. Whether in or out of sleep, something or someone must be causing this. What it is, though, is unknown.