I think it was probably a recent orphan heirloom article of mine in Ancestry Magazine called Rain Goat that made Kaisa Kyläkoski think to tell me about this radio show, and I'm very glad she did.
I just finished listening to this "Detective Stories" episode of New York Public Radio's Radio Lab, and it's a kick. The particular story that Kaisa wrote about is indeed called Goat on a Cow and involves a lost packet of letters that were found strewn along a road -- thanks to the aforementioned goat and cow. It's an orphan heirloom case told in a casual style. Any show that includes sleuthing and mentions of nonchalant cows is a winner to me, and I suspect you'll enjoy it too.
As a bonus, you can also listen to the other two pieces on ancient garbage (turns out the Egyptians were reading stuff a little racier than the Bible -- and oh, by the way, 666 might be the wrong number to fear) and Genghis Khan's DNA. The icing on the cake is that the last piece features DNA-guru Spencer Wells and Tatiana Zerjal (great name, terrific geneticist and charming guest) and provides a behind-the-scenes look at what it's like to drive around Asia asking strangers for their DNA (I did the same on a much smaller scale in Slovakia and thoroughly enjoyed it).
Many thanks to Kaisa for letting me know about this!