During his trip to the Giant's Causeway in Northern Ireland, Professor du Sautoy finds a fundamental truth about the universe written into the rocks. A hidden geometric force underpins all nature, from the structure of honeycombs to Pixar movies.

While so much of life appears random, Du Sautoy shows how it is really governed by the code of chaos, in which small variations can cause vastly different outcomes, often referred to as the "butterfly effect."

What do the proportions of Chartres Cathedral share with the life cycle of the cicada, with how we hear sound, and with the intricately designed nautilus shell? Du Sautoy investigates their sacred numbers and the power of pi.