Numb3rs (2005)

S1E5 Prime Suspect

After a five-year-old girl is abducted during her birthday celebration, Don and Terry take charge of the investigation. They soon enlist Charlie's assistance, as the girl's father, Ethan, is a mathematician. Charlie uncovers the kidnapper's motive when Ethan shares that he is on the verge of cracking Riemann's Hypothesis, a notoriously challenging mathematical problem. Successfully solving it could not only win him a $1 million prize but also compromise internet security and expose the largest financial secret in the world.