Particle physicist Professor Brian Cox asks, ‘What time is it?’ It sounds like the answer ought to be simple, but do we really understand the question?

He visits the ancient Mayan pyramids in Mexico where they built temples to time, finds out that a day is never 24 hours and meets Earth’s very own Director of Time. He also journeys to the beginning of time, and travels deep into the realms of string theory, exploring the very limit of time, subsequently discovering we not only travel through time at the speed of light, but the experience we feel as the passing of time could, in fact, be an illusion.