The case concerns two works, White Palm on Red and Green Snail on Blue, that were among hundreds stolen from a cache of works belonging to one of Matisse’s sons stored at a Paris warehouse shortly after that son died in 1989. Many of those works were recovered; these two turned up at Sotheby’s Paris in 2008 with no line of provenance submitted, and without authentication, the house wouldn’t sell them. So the consignor is suing the Matisse family.