In 1741, a ship called the Saphir sets sail from a port in La Rochelle, France on its way to the New World. On board are thirty crewmembers and two hundred seventy-one slaves. Somewhere off the coast of Santo Domingo, a slave revolt erupts. This little-known moment in history was memorialized in an obscure 18th century painting that hangs in the Saint-Louis Cathedral in La Rochelle. Celebrated filmmaker Jose Luis Guerin peers into this painting to vividly re-tell the story, capturing, in the process, a snapshot of the political, historical, economic and social realities of the time. THE SAPPHIRE OF ST. LOUIS is a remarkable documentary that uses a little painting hidden away in a remote cathedral to open a door on a pivotal moment in history