The worldwide treasure hunt behind the stunning Stein collection on show in Paris

The Grand Palais in Paris is hosting an exceptional exhibition of major modern artworks from the widely scattered collection of the celebrated Stein family of art patrons who settled in the French capital from the US in the early 20th century. The stunning show of works by Renoir, Cézanne, Picasso, Matisse (photo), Manguin and Bonnard - to name but a few - is the fruit of five years of dogged detective work by specialists in France and from the San Francisco Museum of Modern Art and the New York Metropolitan Museum of Art. Joseph Confavreux talks to the team behind this unprecedented worldwide treasure hunt.