Scientists Banting, Best, Collip and Macleod at the University of Toronto as they race for a treatment to cure 13-year-old Leonard Thompson of his life-threatening diagnosis of diabetes.
| Actor | Role |
|---|---|
 Jeremy SchuetzeDr. Frederick Banting | Dr. Frederick Banting |
 Dean PetriwLeonard Thompson | Leonard Thompson |
 Jewel StaiteNurse Anna | Nurse Anna |
 Em HaineNurse May | Nurse May |
 Troy MundleMr. Thompson | Mr. Thompson |
 Duane KeoghJohn Macleod | John Macleod |
 Craig HaasJames Collip | James Collip |
| JJohnny SutherlandCharles Best | Charles Best |
| KKen McNicolDr. Walter Campbell | Dr. Walter Campbell |
 Malaika JacksonLittle Girl's Mother | Little Girl's Mother |
 Victor GarberNarrator (voice) | Narrator (voice) |