Ramanujan's work on infinite series, prime numbers, and elliptic curves revolutionized the field of mathematics. His collaboration with Hardy led to the development of the Hardy-Ramanujan-Rademacher series, which provides an exact formula for the partition function. This work has had a lasting impact on number theory and has influenced generations of mathematicians.

The film begins with Srinivasa Ramanujan (Dev Patel), a young Indian mathematician who had grown up in a poor family in Madras. Despite lacking formal education, Ramanujan's exceptional mathematical abilities are recognized by his peers and he eventually sends his work to Cambridge University.