Episode 5 of "Numb3rs"
s01e05 Prime Suspect
Title: Prime Suspect
Original Air Date: 02/18/2005 on CBS
Director: Lesli Linka Glatter
Writer: Doris Egan
Guest Stars: Jamie McShane (Paul Ballard), Tom Irwin (Dr. Stephen Atwood), Susan Beaubian (FBI Computer Tech #2), Greg Zola (Carl Mittendorf), Murphy Cross (Meredith), Matthew Yang King (FBI Computer Tech #1), Susan Egan (Becky Burdick), Fay Wolf (Kyono), Ian Barford (Mikey), Emma Prescott (Emily Burdick), Adam Smith (FBI Computer Tech #3)
Plot Outline:
When a five-year-old girl is kidnapped from her birthday party, Don and Terry lead the investigation, but must rely on Charlie's help because the girl's father, Ethan, is also a mathematician. Charlie realizes the kidnapper's motive when Ethan reveals he is close to solving Riemann's Hypothesis, a difficult math problem. If solved, the solution could not only earn him $1 million, but could break the code for internet security and unlock the world's biggest financial secret.