Julia's final walk takes her to the remote north-west corner of South Africa. This is the edge of the Kalahari Desert and the setting for Julia's most adventurous undertaking yet. Far away from the major tourist draws of the country, it is an insight into a true African world. Set against the stunning red geology of Augrabies National Park, it's a stark but beautiful walk, encountering simple rural lives and remarkable agriculture, utterly reliant on the broad waters of the Orange River.

• Julia Bradbury