Christopher Nolan's film retells one of the oldest adventure stories ever written: Homer's Odyssey. Ten years after the fall of Troy, the Greek hero Odysseus is still trying to sail home to the island of Ithaca, to the wife and son he left behind twenty years before. The gods are divided over him. Here is a spoiler-free guide to who is who, drawn from the original poem, so you can walk into the film knowing the players without knowing what happens to them.