Casting shadows

When two stubborn boys, one soft the other unbreakable, discover they have the key to save humanity, there is very little that will make them think twice about seeing it through. Life as they know it is far from satisfying and the longing of waking up to sunlight grows more and more unbearable as the endless days in darkness continue. The only thing scarier than living out the rest of their lives in constant fear of dying, is the fear of losing the other. But could they be putting both fears to the test by embarking on a terrifying and agonising journey to save human kind?