There are many reasons that among the hundreds of thousands of cases involving artwork looted by the Nazis the story of Gustav Klimt’s “Adele Bloch-Bauer I” would particularly appeal to filmmakers. For one, there is the mesmerizing gold-flecked painting itself, which set a record price of $135 million when it was sold in 2006. Then there is the David-and-Goliath tale featuring a feisty octogenarian heroine — Ms. Bloch-Bauer’s niece Maria Altmann — taking on a recalcitrant Austrian government. And finally there is the satisfying conclusion. Ms. Altmann gets the portrait back. Justice prevails.

Yet even today, viewers may not realize how rare such justice is when it comes to the return of art looted during the Nazis’ reign of terror to its rightful owners or — as is now more likely, seven decades later — to their descendants.

As the new film “Woman in Gold,” starring Helen Mirren as the indefatigable Maria Altmann, acknowledges in a brief written prologue before the credits roll, more than 100,000 stolen works of art are still unaccounted for.

When Ms. Altmann first sought to reclaim some of her family’s paintings in 1998, there were reasons to think that the odds of restitution — crushingly low for so long — might have finally improved. After decades of neglect or outright opposition to restitution efforts, international public opinion had finally begun to turn in the wake of post-Cold War revelations about continuing malfeasance involving Nazi plunder. Official reports commissioned by both Switzerland and the United States detailed, for example, how the Swiss had reneged on agreements to return hundreds of millions of dollars’ worth of gold stolen by Nazi Germany, while Swiss banks had agreed to a $1.25 billion settlement with Holocaust survivors after being sued for their refusal to return assets deposited for safekeeping during the war. Meanwhile, a new generation, less interested in covering up historical sins, exposed the ways governments, museum officials, dealers and buyers often systematically frustrated attempts to return stolen assets and art to the original owners.