For those of you who’ve asked what happened to our series on the partnership between John Lennon and Paul McCartney, we had to honor a request to take down the episodes due to questions surrounding music rights.

Our six-part series on the torrid relationship of Frida Kahlo and Diego Rivera is now underway. And we'll be following that series with new stories and interviews of many famous collaborations: Jim Henson and Frank Oz working together to create the Muppets. The outsized success of the Kardashians. And the revolutionary story of the other Lenin -- Vladimir Lenin — and his partnership with Leon Trotsky.