February in 1921 Whitaker, Saskatchewan, is colder and bleaker than usual as 13-year-old Lucy May Barber mourns her mother's sudden death. Unable to foresee life without Mama, Lucy decides it's up to her to hold the family together.

But that turns out to be easier said than done, and it isn't long before everything starts going wrong. Papa hires a meddling housekeeper; five-year-old Teddy starts forgetting Mama; 15-year-old Tom gets involved with bootleggers; and Papa buries himself in his work, leaving the children to fend for themselves. In addition, Papa blames their favourite uncle for Mama's death and banishes him from their home.

Lucy fears all is lost, until another tragedy forces her to confront her grief in a different way.