He is a brilliant maths professor with a peculiar problem - ever since a traumatic head injury seventeen years ago, he has lived with only eighty minutes of short-term memory.She is a sensitive but astute young housekeeper who is entrusted to take care of him.Each morning, as the Professor and the Housekeeper are reintroduced to one another, a strange, beautiful relationship blossoms between them.The Professor may not remember what he had for breakfast, but his mind is still alive with elegant equations from the past.He devises clever maths riddles - based on her shoe size or her birthday - and the numbers reveal a sheltering and poetic world to both the Housekeeper and her ten-year-old son.With each new equation, the three lost souls forge an affection more mysterious than imaginary numbers, and a bond that runs deeper than memory.