At a time, when there is a dearth of optimism about the state of our planet, this upbeat documentary offers hope and light.

The film, which won the audience award at Hot Docs 2008, tells of the courage of Nobel Peace prize-winner Wangari Maathai and her part in the evolution of Kenya's environmental and socio-political landscape.

From humble beginnings, Maathai became a force for change in the Seventies by quietly educating and organising groups of women in villages across Kenya to plant trees with her Green Belt Movement - trees that have now grown into tall forests.

Maathai's spirited and peaceful defence of her ideals in subsequent decades, in spite of beatings, imprisonment, threats, and public ridicule by then dictator Moy, is an inspiration.

Longstanding US docu team Alan Dater and Lisa Merton capture the warmth and gutsiness of this amazing woman and show that, yes, apparently complex problems can often have simple solutions. Very refreshing, that.