1922. Fifty-year-old Pastor Martin Gerlach lives with his wife Alma and fourteen-year-old son Benno at Hermannsburg Mission. In the years since his arrival, Martin has built up the biggest and most influential mission in Australia. But Martin's heart is failing. His legs have swollen and he can barely walk. The Lutheran Board in Adelaide tells Martin they cannot help; he must make the journey back to Adelaide himself. A few days later, Martin climbs aboard a dray and settles into a roped-down chair for the journey to Horseshoe Bend. As a crowd sings the Gerlachs, schoolteacher Ignatz, 'Blind' Silas, and young Jamy off, they leave the mission, facing an eight-day trek along the Finke River. Along the way, Benno observes his fellow travellers. Martin, torn between God (deserting him) and the guilt of lost lives, lost culture; Alma, always stoic; Silas (saved, as a child, from an inter-tribal conflict that claimed his mother), preaching a gospel that has nothing to do with his people; Ignatz, hiding his own secrets. As Benno witnesses his father's suffering, he realises he's helpless to fix the problem, or even talk to Martin about what's happening. Now eighty, living alone in a home full of memories, dusty notes and artefacts, Benno is brought back to those days in the desert when his estranged son knocks on his door, his ten-year-old son in tow. As Benno reconnects with his son and grandson, he revisits his past, and tries to understand it all