If you need a good book to read to go along with the show, Priceless: How I Went Undercover to Rescue the World's Stolen Treasure by Robert K. Wittman. Not as exciting as Hercule Poirot but definitely an interesting detective and a good read. Each chapter is about a different case and you'd think after a few the "operation" would start to be the same but they're not. Some art thefts were straight forward, disguise yourself as a black market dealer and earn the trust of the thief and keep the "friendship" long enough to authenticate the painting and then make the arrest. However, his job took him around the world and each country treats art theft differently. Oddly enough his statistics make it sound like The United States takes art theft more seriously than most.
As I've said before art theft fascinates me. Why people steal art and then the hunting down of the art is like a real life Indiana Jones but with less faces melting off. As for the why people steal art, lot's of studies and papers have been written about it. Here's an interesting article about it that was written shortly after a theft of seven paintings in Rotterdam back in 2012. The alleged art thieves were arrested in 2013 and one of them confessed to burning all of the paintings. The paintings were never recovered and it's unknown if they were actually burnt. What is it about art that makes it so valuable that people would go to such great lengths to steal it?