In 1990 two men dressed as police officers walked out of Boston’s Isabella Stewart Gardner Museum with 13 works, including a Vermeer and Rembrandt’s only known seascape, in the largest theft of private property in history. It remains unsolved. But as this episode explains, walking out the door is the easy part. A famous painting weighs a few kilograms and cannot be sold on any open market.

The hosts explore what actually happens to stolen masterpieces, from their use as underworld collateral in weapons and drug deals to the obsessives, hoarders, and critics who steal for reasons that have nothing to do with money, and the nation-states that loot on an industrial scale.

• How stolen art becomes a bearer bond stored in free ports in Geneva or Singapore, and why ransom attempts usually end in stings
• Stephane Breitwieser’s 238 thefts and the mother who fed Renaissance paintings into a garbage disposal
• John Tillmann’s 10,000 stolen objects, including a 5,000-year-old Egyptian mummy, and the 2003 Whitworth thieves who left a note about poor security
• Nazi looting, the Gurlitt apartment discovery of some 1,500 works, Russian looting in Ukraine, and the Elgin Marbles repatriation debate
• Why only about 10 percent of stolen art is recovered, Italy’s Carabinieri art squad and its Leonardo database, and the 25-year hunt for the Marie Antoinette Breguet watch