In British India in the early 20th century, a self-taught mathematical genius named Srinivasa Ramanujan faces considerable hardship due to his impoverished background. Determined to prove his worth and share his discoveries with the world, he sends a letter full of his mathematical theorems to G.H. Hardy, a prominent professor at Cambridge University. Hardy is immediately impressed and invites Ramanujan to England. Despite opposition from his family and the looming threat of World War I, Ramanujan travels to Cambridge, only to encounter cultural isolation, racial prejudice, and resistance from skeptical peers.

Once at Cambridge, Ramanujan finds an unlikely ally in Hardy, who becomes both a mentor and a rigorous critic. The two mathematicians develop a profound yet challenging partnership, struggling to validate Ramanujan's groundbreaking work. Hardy urges Ramanujan to provide proofs for his theories, which are often derived from intuitive methods unfamiliar to Western mathematicians. The strain of academic rigor, homesickness, and deteriorating health take their toll on Ramanujan, but his perseverance and brilliance eventually shine through. Through their collaboration, Ramanujan’s extraordinary contributions to mathematics begin to gain recognition, fundamentally impacting both their lives and the field of mathematics.