The only thing Samantha has run is a ladder in her tights. Suzie cannot even run for a bus, and the only thing Sharon can run is paint, down a wall, but somehow, they have each agreed to run the London Marathon next year.

Samantha wants to impress a new colleague, Suzie wants to better her life, and Sharon wants another baby. The idea of running twenty-six miles is frightening to start with, but once they consider the reward, they each look for a running buddy, and join, Jogging Buddy. The training starts and it does not come without its problems. The three girls, from three very different walks of life, unite and name themselves Mum Runners. Samantha gets an injury, Suzie has a car crash, and Sharon has an unexpected visitor—but this does not stop their determination to cross the finish line. Through the training, they become best friends for life.