The Pastures of Osirians

Local Villager, Tristan finds an ancient tomb which belonged to the god Osiris. Inside it is a gem, which is unfortunately cursed. An Entity was imprisoned there, until now as it releases the curse upon The Village of Richfield. Crops die, gods awake, and the heavens break as more time passes by. The only way to restore Richfield to the way it was is for the descendant to defeat Osiris. But The Doctor is unaware of this, and gives himself to save his friends, losing his life to Osiris. Tegan and Turlough are left to fend for themselves and find the descendant fast or time will run out for them too... But what happens when Tegan is taken in as a new sacrifice? Turlough must save his friends and ressurect Richfield, when he learns more about his past. He is the last survivor, and he is the descendant....