The question of whether there is a number at the root of the universe, a primal number that everything in the world hinges on, has exercised many great minds of the twentieth century, among them the groundbreaking physicist Wolfgang Pauli and the famous psychoanalyst Carl Jung. Their obsession with the power of certain numbers - including 137, which describes the atom's fine-structure constant and has great Kabalistic significance - led them to develop an unlikely friendship and to embark on a joint mystical quest reaching deep into medieval alchemy, dream interpretation and the Chinese Book of Changes. "137" explores the profound intersection of modern science with the occult but above all it is the tale of an extraordinary, fruitful friendship between two of the greatest thinkers of our times.